Al Unser Jr. drove to his third straight victory yesterday, winning another strategic battle with teammate Bobby Rahal in the inaugural Denver Grand Prix.

Unser, adding to his CART-PPG Indy-car series point lead, handled the 90-degree heat, the thin air of the Mile High City and the demanding 1.9-mile, 16-turn downtown street circuit to beat Danny Sullivan by 28 seconds.

Rahal, who finished second to Unser two weeks ago at Michigan International Speedway in the fastest 500-mile race ever, dueled with Unser through most of yesterday's 80-lap, 152-mile race.

The race came down to late pit stops. Rahal pitted first, while Unser waited as long as he could and got the benefit of a caution flag.

Unser, who earned his 14th career victory and fifth of the season, gave up the lead to Rahal when he made his final scheduled pit stop on Lap 61.

He left the pits trailing Rahal by 16.83 seconds and proceeded to slice into that margin on each lap, moving up behind the nearly identical Chevrolet-powered Lola before Rahal was forced to pit for fuel on Lap 73.

Unser easily held off Sullivan, who in turn stayed ahead of Rahal.

A sellout crowd of about 55,000 watched the race, in which there were eight lead changes, the most in an Indy-car race since 1988.

Unser, who won $123,866, averaged 71.24 mph -- the slowest winning time in CART history. Sixteen of the 28 starters were running at the end.

Teo Fabi, who started from the pole, led the first seven laps as Mario Andretti moved up from fourth place to challenge for the top spot.

At the start of Lap 8, Fabi's brakes failed and he drove straight across the track, running through one tire wall and slamming into another. He was not injured.

"I'm happy to be in one piece," he said. "The brake pedal went down to the floor and I didn't have time to pump it up. It was quite a big impact."

That incident gave Andretti the lead and brought out the only full-course caution flag.

Defending series champion Emerson Fittipaldi of Brazil, who ran among the leaders much of the way, was sidelined on Lap 60 with a broken half-axle while running sixth.

Unser earned 20 points for the win and one for leading the most laps (34), building his season margin over second-place Michael Andretti to 147-114. Five of 16 races remain.

Dean Hall and Jon Beekhuis crashed together early in the race, but were cleared from the track without having to put out the pace car.

Belgian Grand Prix: Brazil's Ayrton Senna won the race for the third consecutive time, beating world champion Alain Prost of France and extending his Formula One standings lead.

Senna, driving a McLaren-Honda, led all the way, driving cautiously over the 44 laps in Spa-Francorchamps. He finished 3.550 seconds ahead of Prost, in a Ferrari.

Senna's teammate, Gerhard Berger of Austria, was 28.462 seconds back in third after a tough battle with Alessandro Nannini of Italy in a Ford.

Brazilians Nelson Piquet, in a Ford, and Mauricio Gugelmin, in a Judd, finished fifth and sixth.

The race was marred by several crashes, but no driver was seriously injured.

The victory increased Senna's point total to 63 in the driving standings. Prost is second with 50 and Berger third with 33.

The race had to be started three times. On the first attempt, Piquet hit Briton Nigel Mansell near the opening hairpin, sending six cars off the track.

On the second start, 20 minutes later, Italy's Paolo Barilla crashed. His Minardi caught fire and the track was littered with debris and oil. The fire was quickly brought under control and Barilla was not seriously injured.

On the third start, Senna took the lead and steadily widened it over Berger, who held off Prost until the 13th lap. Prost then slipped past Berger and set off in hot pursuit of Senna, who maintained control on the 4.312-mile track through the Ardennes hills. He finished in 1 hour 26 minutes 31.997 seconds, an average of 131.272 mph.