It’s just a matter of time before the two-time defending champion Los Angeles Lakers have the plug pulled on their life support and their throne goes dark. Drs. Nowitzki, Terry and Stojakovic gave the first yank Friday night. In a game that fans no doubt wished had gone on longer for its entertainment value, the Mavericks overcame a seven-point deficit in the final five minutes and pulled off a 98-92 victory to go ahead, 3-0, in their Western Conference semifinal series against the Lakers. No team in NBA history has lost a 3-0 lead in any round. The Mavericks’ first chance to vanquish the Lakers comes on Mother’s Day. The last time the Lakers were swept in a playoff series was in 1999 by the San Antonio Spurs in the West semifinals. Before the largest crowd in American Airlines Center history (21,156), the Mavericks got another gigantic night from Dirk Nowitzki, who hit a lefty hook shot with 1:23 to go that put the Mavericks ahead for good, 93-91. He finished with 32 points and nine rebounds, hitting all manner of shots.