Tomba, who was 28 on Monday, had a combined time of 1min 44.73sec, nearly a second and a half ahead of the pack.
The Italian, who had pain-killing injections before the race, beat Austria's Thomas Sykora, who clocked 1:46.22, into second place. Slovenia's Jure Kosir came third in 1:46.50.
The win gave Tomba a clean sweep of slaloms this season and his fifth in a row after he won the final two events of last season. He stretched his lead in the overall standings over Michael von Gruenigen, of Switzerland, who was fifth yesterday.
Conditions on the 180-metre Schlegelkopf run were difficult: a layer of artificial snow and ice was covered overnight and during the day with constant snowfalls. There is a second slalom at Lech today before the men move to Alta Badia in Italy esh tomorrow for a giant slalom.Reuse content