MONZA, Italy — Sebastian Vettel of Toro Rosso will become the youngest Formula One driver to start from the pole position after setting the fastest qualifying session today for the Italian Grand Prix.

The 21-year-old German driver took advantage of the rain-drenched Monza circuit to earn the first pole for him and the team. McLaren's Heikki Kovalainen took second and Red Bull's Mark Webber came third.

"What can I say, I never dreamed of being on pole. It's unbelievable," Vettel said.

Vettel's lap time of 1 minute, 37.555 seconds over the 3.6-mile circuit was nearly 16 seconds off the pace set by eventual winner Fernando Alonso last year.

Overall F1 leader Lewis Hamilton of McLaren will start Sunday's race from 15th place and Ferrari's Kimi Raikkonen from 14th after both drivers failed to compete in the second session because of the rain.

Rain is also expected for Sunday's race.

Ferrari's Felipe Massa, who trails Hamilton by two points, will start sixth. He can take over the championship lead with a steady drive in treacherous conditions.

Vettel jumped out of his car pumping his fists to receive congratulations from fellow drivers. He then ran out into pit lane to celebrate with his team, who cheered as the final qualifying session timed out.

"I was joking with my engineers, saying if it's wet, we have to go for pole position," said Vettel, who will replace David Coulthard at Red Bull next year. "We didn't know what to expect, how wet it was, how much rain there would be. It was so difficult today, especially with the traffic ... it was nearly impossible to see anything."

Vettel's teammate, Sebastien Bourdais, finished fourth.

Drivers not only had to deal with slippery conditions on the fastest circuit, but also poor visibility with wet spray shooting behind the cars.

Raikkonen and Hamilton swerved wildly off track at corner No. 10 as they pushed to make the cut for the final session with the rain intensifying during the second session.

Hamilton posted his worst qualifying result in 31 F1 races. He switched to the extreme wet tires early in the second session.

"We thought it was the right way to go at the time because it was getting dryer but the grip-level was poor so I came in and switched to extreme (wet tires)," Hamilton said. "By the time I got out, it had begun to rain and I just missed the window when the track was the fastest."

Raikkonen, the defending F1 champion who signed a one-year contract extension Friday that will keep him at Ferrari through 2010, trails Hamilton by 19 points.

BMW Sauber's Robert Kubica, who is 18 points behind Hamilton in third place overall, also failed to emerge from the second session and will start 11th.

Toyota's Timo Glock was fastest in the final practice before the rain. Cars were constantly slipping off a track overflowing with water, forcing teams back to their garages with half of the 60-minute session still to run.