overtook Coulthard for fourth on the outside at the fast right-hand Agip corner that lap. Montoya made his pit stop on lap 22. However, his pit stop proved problematic: the signal lights at his pit box stopped working, causing the Williams refuller to switch to the fuel rig for Ralf Schumacher due a regulator failure. This meant Montoya remained stationary for 20 seconds longer than usual and one-and-a-half times more fuel went into his car. Ralf Schumacher took the lead with Michael Schumacher second; Montoya fell to fourth. One lap later, Michael Schumacher took his pit stop and exited with a fuel pressure problem that saw him retired at the side of the main straight. Burti lost control of his car and was beached in the gravel trap against the tyre barrier at Nordkurve on the following lap. On lap 24, Ralf Schumacher made his pit stop and rejoined with a 10-second advantage. Villeneuve, Button and Alonso all made their pit stops on that lap. Alonso encountered a problem when leaving his pit box: the Minardi refuelling valve had a problem, and his car's afterburner remained on, though the flames extinguished themselves when Alonso accelerated out of the pit lane. Montoya pulled over to the side of the track on lap 25, with smoke billowing from his engine, and retired. His retirement moved Coulthard to third. Fisichella made a pit stop from fourth on lap 27 and fell to fifth behind Villeneuve. Marques retired with a gearbox problem on the same lap. Coulthard made a pit stop on lap 28 and immediately became the race's next retirement when he accelerated away from his pit box with a blown engine. The resulting event saw him stop at the side of the circuit. Panis made his pit stop on the 32nd lap and emerged behind Button and Alesi. Barrichello became the final driver to make a scheduled pit stop a lap later and was delayed for 12 seconds because the Ferrari fuel hose closed itself. This meant Barrichello's team switched to a functioning refuelling rig. At the completion of lap 33, with the scheduled pit stops completed, the race order was, Ralf Schumacher, Barrichello, Villeneuve, Fisichella, Button and Alesi. Trulli became the final retirement after stopping at the side of the circuit due to a hydraulic pump failure on lap 35. Ralf Schumacher began to reduce his pace by lap 37 but