Entering the race, Prost led the Drivers' Championship by 16 points, 76 to 60. Senna had won six races to Prost's four but had accumulated far fewer consistent points finishes across the season. To retain his championship Senna had to win both this race and the final round in Australia; any other result would give Prost the title regardless of his own finish. Prost, for his part, had already informed team principal Ron Dennis that he would not leave the door open if Senna challenged him — a departure from his previous approach of avoiding intra-team contact.
The two McLarens dominated qualifying as expected. Senna took pole position by more than one and a half seconds over his teammate, while Prost focused his car setup on race performance rather than outright qualifying pace, accepting a second-row start was available to the Ferraris of Gerhard Berger and Nigel Mansell. Alessandro Nannini qualified sixth in his Benetton-Ford, equipped with a development HBA4 V8 engine for qualifying.
Prost had his Gurney flap removed before the start to improve straight-line speed, without Senna's knowledge. His race setup proved superior: he got the better start, immediately negating Senna's pole advantage, while Gerhard Berger briefly ran alongside Senna through the opening corner before being repelled. Over the first half of the race Prost systematically extended his lead to nearly six seconds. Senna lost further time at his pit stop, emerging behind his teammate by a larger margin still.
With new tyres, Senna began closing the gap. Berger's Ferrari retired on lap 34 with gearbox failure; Mansell's followed nine laps later with an engine failure. By lap 40 Senna had caught Prost, and for the next five laps the gap held at roughly one second as both drivers sought an opportunity. Prost held an advantage on the straights while Senna's higher-downforce setup gave him the edge through corners. On lap 47 Senna used his cornering advantage through Spoon Corner and the 130R to draw right onto Prost's gearbox. At the chicane, Senna dived to the inside. He never came fully alongside — his front wheels remained just behind Prost's — and when Prost turned in to the apex the two cars made contact. Both stalled and came to rest at the mouth of the chicane escape road, having missed the chicane entry.
Prost unbuckled and walked away from his car. Senna gestured to marshals to push him along the escape road; once moving, he bump-started his McLaren and accelerated back onto the track, weaving through the chicane bollards. His front wing was damaged, necessitating a pit stop for a replacement nose. Despite the stall, the time lost waiting for the push, and the pit stop, Senna rejoined only five seconds behind new race leader Alessandro Nannini. He caught and passed the Benetton two laps after the pit stop, in almost exactly the same corner complex where the collision with Prost had occurred, and crossed the line first.
Race stewards disqualified Senna immediately after the race for two offences: missing the chicane and gaining an advantage, and receiving outside assistance from marshals to restart. Nannini was awarded the victory — his only Formula One win; his career would end almost exactly a year later when a helicopter accident severed his right forearm. Patrese was elevated to second and Boutsen to third.
Senna and McLaren appealed, arguing that the disqualification was unjust and cost the team prize money and bonus sponsorship. At a FISA hearing in Paris later that week, the disqualification was upheld and an additional US$100,000 fine and a suspended six-month ban were imposed. FISA also labelled Senna a dangerous driver. Senna publicly alleged that FISA President Jean-Marie Balestre had influenced the stewards' decision to benefit his fellow Frenchman Prost; Balestre and the stewards denied this at the time. In a 1996 interview Balestre acknowledged that he had intervened.
With the disqualification it became mathematically impossible for Senna to overtake Prost's points total, and the 1989 Drivers' Championship was awarded to Prost. The collision itself has never been definitively adjudicated: whether Prost moved deliberately to close the door, whether Senna was overambitious, or whether it was a racing incident between two deeply embittered teammates remains a matter of debate in Formula One history.
Only eleven of the 26 starters were still classified at the finish. Nelson Piquet took fourth despite starting eleventh, benefiting from the high attrition rate. Derek Warwick climbed from 25th on the grid to seventh after removing virtually all downforce from his Arrows for additional straight-line speed.