The 1985 Belgian Grand Prix was a Formula One motor race held at Spa-Francorchamps on 15 September 1985. It was the thirteenth round of the 1985 FIA Formula One World Championship. The race was the 43rd Belgian Grand Prix, the 31st to be held at Spa and the second since the circuit had been rebuilt and re-opened at half its original length in 1979. The race was held over 43 laps of the seven kilometre circuit for a total race distance of 301 kilometres.
The race was won by Brazilian driver Ayrton Senna driving a Lotus 97T. It was Senna's second World Championship victory and the first of five he would win at Spa-Francorchamps. Senna won by 28 seconds over British driver Nigel Mansell driving a Williams FW10. Third was World Championship points leader, French driver Alain Prost driving a McLaren MP4/2B. The win promoted Senna to third in the drivers' standings and third place allowed Prost to expand his lead over Ferrari driver Michele Alboreto to 16 points.
Originally scheduled to take place on 2 June 1985, the Grand Prix was rescheduled for September after the recently resurfaced track became damaged during the race weekend. Fédération Internationale du Sport Automobile (FISA), the governing body of Formula One, was queried about the resurfacing work and replied it would approve if race organisers complied with a regulation that mandates any such work occur 60 days beforehand. Local bureaucracy and a harsh winter caused delays to the work, which were reportedly finished ten days before the event's scheduled date of 31 May, and forced a cancellation of a pre-race test session at the circuit. Organisers did not refer the incident to the Fédération Internationale de l'Automobile and went ahead.
Prost took pole position, averaging 135.929 mph (218.756 km/h) from Senna with Nelson Piquet qualifying third in his Brabham BT54, with Alboreto fourth in his Ferrari 156/85. Rain fell before the race leaving the grid to form on a damp track with wet-weather tyres for the first time since Senna won in Portugal. Senna won the start from Piquet but the Brabham spun at the first corner. Senna led from Prost, Mansell and the two Ferraris of Alboreto and Stefan Johansson. The Ferraris were soon out, from a broken clutch and engine respectively. Meanwhile Johansson retired after spinning off at the end of the Kemmel Straight on Lap 8. Prost dropped behind the two Williams FW10s as the field pitted for dry tyres. Late in the race rain fell again and Senna expanded his lead. Keke Rosberg dropped to fourth with a brief pit visit with a brake problem and they finished in that order. Fifth had been Thierry Boutsen until his Arrows A8 broke its gearbox. Piquet claimed fifth from Derek Warwick in a Renault RE60B, Warwick scored the last point for the original factory Renault team. Twelve cars finished the race, including for the first time a Minardi as Pierluigi Martini finished twelfth in his Minardi M185. A further two cars, Boutsen and the crashed Ligier JS25 of Jacques Laffite were also classified as finishers. Huub Rothengatter's Osella FA1G fell one lap short of being classified.
Classification
Qualifying
Times recorded on Friday qualifying session before postponement (31 May 1985)
{| class="wikitable sortable mw-collapsible mw-collapsed" style="font-size: 95%;"
|-
! Pos !! No !! Driver !! Constructor !! Time
|-
! 1
| 27
| data-sort-value="alb" | Michele Alboreto
|Ferrari
| 1:56.046
|-
! 2
| 11
| data-sort-value="de A" | Elio de Angelis
|Lotus-Renault
| 1:56.273
|-
! 3
| 12
| data-sort-value="sen" | Ayrton Senna
|Lotus-Renault
| 1:56.473
|-
! 4
| 15
| data-sort-value="tam" | Patrick Tambay
|Renault
| 1:56.586
|-
! 5
| 28
| data-sort-value="joh" | Stefan Johansson
|Ferrari
| 1:57.506
|-
! 6
| 6
| data-sort-value="ros" | Keke Rosberg
|Williams-Honda
| 1:57.705
|-
! 7
| 7
| data-sort-value="piq" | Nelson Piquet
|Brabham-BMW
| 1:58.122
|-
! 8
| 25
| data-sort-value="str" | Andrea de Cesaris
|Ligier-Renault
| 1:58.302
|-
! 9
| 17
| data-sort-value="ber" | Gerhard Berger
|Arrows-BMW
| 1:58.343
|-
!10
|1
| Niki Lauda
|McLaren-TAG
|1:58.374
|-
! 11
| 5
| data-sort-value="man" | Nigel Mansell
|Williams-Honda
| 1:58.658
|-
! 12
| 18
| data-sort-value="bou" | Thierry Boutsen
|Arrows-BMW
| 1:58.874
|-
! 13
| 16
| data-sort-value="war" | Derek Warwick
|Renault
| 1:59.129
|-
! 14
| 19
| data-sort-value="fab" | Teo Fabi
|Toleman-Hart
| 2:00.592
|-
! 15
| 26
| data-sort-value="laf" | Jacques Laffite
|Ligier-Renault
| 2:00.729
|-
! 16
| 23
| data-sort-value="che" | Eddie Cheever
|Alfa Romeo
| 2:00.782
|-
! 17
| 22
| data-sort-value="Pat" | Riccardo Patrese
|Alfa Romeo
| 2:01.396
|-
! 18
| 8
| data-sort-value="sur" | Marc Surer
|Brabham-BMW
| 2:01.555
|-
! 19
| 30
| data-sort-value="dan" | Jonathan Palmer
|Zakspeed
| 2:04.990
|-
! 20
| 4
| data-sort-value="ghi" | Stefan Bellof
|Tyrrell-Renault
| 2:05.070
|-
! 21
| 24
| data-sort-value="rot" | Piercarlo Ghinzani
|Osella-Alfa Romeo
| 2:05.088
|-
! 22
| 3
| data-sort-value="bru" | Martin Brundle
|Tyrrell-Renault
| 2:05.782
|-
!23
|9
| Manfred Winkelhock
|RAM-Hart
|2:06.771
|-
! 24
| 29
| data-sort-value="mar" | Pierluigi Martini
|Minardi-Motori Moderni
| 2:12.279
|-
!
| 2
| data-sort-value="pro" | Alain Prost
|McLaren-TAG
| no time
|-
!
| 10
| data-sort-value="all" | Philippe Alliot
|RAM-Hart
| no time
|}
Rescheduled qualifying (13 and 14 September 1985)
{| class="wikitable sortable" style="font-size: 95%;"
|-
! Pos !! No !! Driver !! Constructor !! Q1 !! Q2 !! Gap
|-
! 1
| 2
| data-sort-value="pro"| Alain Prost
| McLaren-TAG
| 1:56.563
| 1:55.306
|data-sort-value="0.001" align="center"| —
|-
! 2
| 12
| data-sort-value="sen"| Ayrton Senna
| Lotus-Renault
| 2:00.710
| 1:55.403
| +0.097
|-
! 3
| 7
| data-sort-value="piq"| Nelson Piquet
| Brabham-BMW
| 1:56.643
| 1:55.648
| +0.342
|-
! 4
| 27
| data-sort-value="alb"| Michele Alboreto
| Ferrari
| 1:56.999
| 1:56.021
| +0.715
|-
! 5
| 28
| data-sort-value="joh"| Stefan Johansson
| Ferrari
| 1:56.585
| 1:56.746
| +1.279
|-
! 6
| 18
| data-sort-value="bou"| Thierry Boutsen
| Arrows-BMW
| 1:59.046
| 1:56.697
| +1.391
|-
! 7
| 5
| data-sort-value="man"| Nigel Mansell
| Williams-Honda
| 1:56.727
| 1:56.996
| +1.421
|-
! 8
| 17
| data-sort-value="ber"| Gerhard Berger
| Arrows-BMW
| 1:56.770
| data-sort-value=9:99|
| +1.464
|-
! 9
| 11
| data-sort-value="de A"| Elio de Angelis
| Lotus-Renault
| 1:58.852
| 1:57.322
| +2.016
|-
! 10
| 6
| data-sort-value="ros"| Keke Rosberg
| Williams-Honda
| 1:57.582
| 1:57.465
| +2.159
|-
! 11
| 19
| data-sort-value="fab"| Teo Fabi
| Toleman-Hart
| 1:57.588
| 1:57.857
| +2.282
|-
! 12
| 8
| data-sort-value="sur"| Marc Surer
| Brabham-BMW
| 2:00.154
| 1:57.729
| +2.423
|-
! 13
| 15
| data-sort-value="tam"| Patrick Tambay
| Renault
| 1:58.105
| 1:59.335
| +2.799
|-
! 14
| 16
| data-sort-value="war"| Derek Warwick
| Renault
| 1:59.761
| 1:58.407
| +3.101
|-
! 15
| 22
| data-sort-value="Pat"| Riccardo Patrese
| Alfa Romeo
| 1:59.703
| 1:58.414
| +3.108
|-
! 16
| 20
| data-sort-value="ghi"| Piercarlo Ghinzani
| Toleman-Hart
| 1:58.820
| 1:58.706
| +3.400
|-
! 17
| 26
| data-sort-value="laf"| Jacques Laffite
| Ligier-Renault
| 2:01.745
| 1:58.933
| +3.627
|-
! 18
| 25
| data-sort-value="str"| Philippe Streiff
| Ligier-Renault
| 2:00.599
| 1:59.245
| +3.939
|-
! 19
| 23
| data-sort-value="che"| Eddie Cheever
| Alfa Romeo
| 2:00.861
| 1:59.370
| +4.064
|-
! 20
| 9
| data-sort-value="all"| Philippe Alliot
| RAM-Hart
| 1:59.626
| 1:59.755
| +4.320
|-
! 21
| 3
| data-sort-value="bru"| Martin Brundle
| Tyrrell-Renault
| 2:00.950
| 2:01.364
| +5.644
|-
! 22
| 30
| data-sort-value="dan"| Christian Danner
| Zakspeed
| 2:05.059
| 2:07.046
| +9.753
|-
! 23
| 24
| data-sort-value="rot"| Huub Rothengatter
| Osella-Alfa Romeo
| 2:06.083
| 2:05.776
| +10.470
|-
! 24
| 29
| data-sort-value="mar"| Pierluigi Martini
| Minardi-Motori Moderni
| 2:06.007
| 2:06.606
| +10.701
|}
Race
{| class="wikitable" style="font-size: 95%;"
|-
! Pos !! No !! Driver !! Constructor !! Laps !! Time/Retired !! Grid !! Points
|-
! 1
| 12
| Ayrton Senna
| Lotus-Renault
| 43
| 1:34:19.893
| 2
| 9
|-
! 2
| 5
| Nigel Mansell
| Williams-Honda
| 43
| + 28.422
| 7
| 6
|-
! 3
| 2
| Alain Prost
| McLaren-TAG
| 43
| + 55.109
| 1
| 4
|-
! 4
| 6
| Keke Rosberg
| Williams-Honda
| 43
| + 1:15.290
| 10
| 3
|-
! 5
| 7
| Nelson Piquet
| Brabham-BMW
| 42
| + 1 lap
| 3
| 2
|-
! 6
| 16
| Derek Warwick
| Renault
| 42
| + 1 lap
| 14
| 1
|-
! 7
| 17
| Gerhard Berger
| Arrows-BMW
| 42
| + 1 lap
| 8
|
|-
! 8
| 8
| Marc Surer
| Brabham-BMW
| 42
| + 1 lap
| 12
|
|-
! 9
| 25
| Philippe Streiff
| Ligier-Renault
| 42
| + 1 lap
| 18
|
|-
! 10
| 18
| Thierry Boutsen
| Arrows-BMW
| 40
| Gearbox
| 6
|
|-
! 11
| 26
| Jacques Laffite
| Ligier-Renault
| 38
| Accident
| 17
|
|-
! 12
| 29
| Pierluigi Martini
| Minardi-Motori Moderni
| 38
| + 5 laps
| 24
|
|-
! 13
| 3
| Martin Brundle
| Tyrrell-Renault
| 38
| + 5 laps
| 21
|
|-
!
| 24
| Huub Rothengatter
| Osella-Alfa Romeo
| 37
| + 6 laps
| 23
|
|-
!
| 22
| Riccardo Patrese
| Alfa Romeo
| 31
| Engine
| 15
|
|-
!
| 23
| Eddie Cheever
| Alfa Romeo
| 26
| Gearbox
| 19
|
|-
!
| 15
| Patrick Tambay
| Renault
| 24
| Gearbox
| 13
|
|-
!
| 19
| Teo Fabi
| Toleman-Hart
| 23
| Throttle
| 11
|
|-
!
| 11
| Elio de Angelis
| Lotus-Renault
| 17
| Turbo
| 9
|
|-
!
| 30
| Christian Danner
| Zakspeed
| 16
| Gearbox
| 22
|
|-
!
| 9
| Philippe Alliot
| RAM-Hart
| 10
| Accident
| 20
|
|-
!
| 28
| Stefan Johansson
| Ferrari
| 7
| Spun off
| 5
|
|-
!
| 20
| Piercarlo Ghinzani
| Toleman-Hart
| 7
| Accident
| 16
|
|-
!
| 27
| Michele Alboreto
| Ferrari
| 3
| Clutch
| 4
|
|-
!
| 1
| Niki Lauda
| McLaren-TAG
|
| Driver injured
|
|
|-
!colspan="8"|
|}
Championship standings after the race
;Drivers' Championship standings
{| class="wikitable" style="font-size: 95%;"
|-
! Pos
! Driver
! Points
|-
| 1
| Alain Prost
| align="right"| 69
|-
| 2
| Michele Alboreto
| align="right"| 53
|-
| 3
| Ayrton Senna
| align="right"| 32
|-
| 4
| Elio de Angelis
| align="right"| 31
|-
| 5
| Keke Rosberg
| align="right"| 21
|-
!colspan=4|Source:
|}
;Constructors' Championship standings
{| class="wikitable" style="font-size: 95%;"
|-
! Pos
! Constructor
! Points
|-
| 1
| McLaren-TAG
| align="right"| 83
|-
| 2
| Ferrari
| align="right"| 77
|-
| 3
| Lotus-Renault
| align="right"| 63
|-
| 4
| Williams-Honda
| align="right"| 34
|-
| 5
| Brabham-BMW
| align="right"| 26
|-
!colspan=4|Source: