As part of the 10-year lease extension the Oakland Athletics signed in July to remain at O.Co Coliseum, owner Lew Wolff vowed to continue seeking a new ballpark for the franchise.

The extension was not expected. The team reached agreement on a 10-year lease extension to remain in a facility that has experienced sewage and lighting problems in recent seasons.

Outgoing commissioner Bud Selig said a new ballpark must be on the frontburner for the Athletics to remain competitive. The A's have played in the Coliseum since 1968 and are in contention for the American League West division title.

"This is always something I wanted to get resolved before I leave office, which is another 5 1/2 or six months," Selig said during a vist to Oakland and fraternity brother Wolff on Tuesday. "I've always said the local club, they know their market best."

Following threats that the team could move from Oakland concessions were made for the team to pay reduced rent. The A's considered San Jose, and the city is appealing a judge's decision that the San Francisco Giants own the territorial rights to that city, preventing the Athletics from relocating there -- for now.

"They've done a remarkable job under the circumstances," Selig said. "One of the reasons for the resurgence of this sport, there are multiple reasons, are the new stadiums. ... I wish it had been resolved. I understand people's frustrations, I do understand. There's a lot of history here."

The Athletics are co-tenants with the Oakland Raiders, who are on a one-year lease and looking at other cities as options due to a stalemate in regional stadium project plans.

The NFL's San Francisco 49ers last opened new Levi's Stadium in Santa Clara.