Memphis Grizzlies' Mike Conley (R) makes a pass around San Antonio Spurs' Antonio McDyess, Tim Duncan and Gary Neal (L-2nd R) during the second half of Game 4 of their Western Conference first round NBA basketball playoffs in Memphis, Tennessee April 25, 2011. REUTERS

MEMPHIS, April 25 - Western Conference top seeds San Antonio were pushed to the brink of elimination from the first round of the NBA playoffs after the Memphis Grizzlies took a 3-1 series lead with a 104-86 win over the Spurs on Monday.

In Dallas, the Mavericks took a 3-2 series lead over the Portland Trail Blazers after a 93-82 victory and will get the chance to close out the series in Portland on Thursday.

The Grizzlies finished the regular season eighth in the West and were not expected to be a major test for the Spurs but their Game Four win puts them in a commanding position in their best-of-seven series.

Memphis were too big and athletic for the Spurs and blew the game open in the third quarter where they outscored San Antonio 30-15.

Mike Conley led Memphis with 15 points, with four others joining him in double figures, as the Grizzlies close in on their first NBA playoff series win.

"We're a team that doesn't get a lot of attention," Conley told reporters. "We've been playing great and we're able to beat good teams like San Antonio. We just have to do it one more time."

The Spurs got 23 points from Tony Parker but Tim Duncan struggled with just six points and seven rebounds.

Game Five is on Wednesday in San Antonio.

The Mavericks blew a 23-point lead in the final 13 minutes of Game Four to lose on Saturday but regrouped with an inspired second half to take a 3-2 series advantage.

Dallas got 25 points from Dirk Nowitzki and 20 from Jason Terry as they outscored the Blazers 31-20 in the third to take control of the game.

Brandon Roy, who was coming off a spectacular performance in Game Four when he tallied 18 of his 24 points in the fourth quarter, managed just five on Monday.