SAN ANTONIO (Reuters) - The San Antonio Spurs squandered a big lead in the fourth quarter, but had veteran star Tim Duncan to thank for settling their nerves in overtime.

The Spurs ground out a 93-89 overtime win over the Memphis Grizzlies and took a 2-0 lead in the NBA Western Conference finals on Tuesday.

Up by 14 in the fourth quarter, the Spurs failed to score in the last four minutes of regulation and were pushed to overtime by the rallying Grizzlies.

However, Duncan scored his team's first six points in the extra session to put the Spurs back on track for the Game Two win.

The series now shifts to Memphis for Game Three on Saturday. The Grizzlies have yet to lose a home game during this post-season.

Despite trailing for most of Game Two, the Grizzlies ended the fourth quarter on a high and put in seven unanswered points.

But they lost momentum in overtime and their hopes disappeared when Jerryd Bayless missed a potential game-tying three-pointer in the closing seconds.

Both Bayless and Mike Conley Jr had a team-leading 18 points, while key forward Zach Randolph finished with 15 and 18 rebounds.

The Spurs' point guard Tony Parker added 15 points, 18 assists and three steals.