PHOENIX -- Major League Baseball Commissioner Bud Selig said Saturday he was not certain the Cubs could complete their sale to prospective owner Tom Ricketts by Opening Day.

Selig, who was at the Cubs' game against the Brewers, said he had yet to meet Ricketts, who has exclusive negotiating rights to purchase the team from the Tribune Company and chief executive Sam Zell. The package, which includes the Cubs and Wrigley Field, is expected to cost $900 million.

"It's moving forward," Selig said. "There's ongoing discussions with the Ricketts family and Tribune Company people, and that's where it is right now. It hasn't moved from there.

"It still hasn't come close to us [for approval]. But I'm very anxious for it to proceed, and I think [the sale] is in everybody's best interest."

Selig said he did not have a timetable as to when the sale would be completed.

"One can be hopeful about Opening Day, but I'm not sure they'll make it," Selig said. "It's up to the parties. There's a lot of conversations going on."

The parties are still negotiating the economic issues, Selig said.

Ricketts has to be approved by a three-quarters vote of baseball owners. A bankruptcy judge also may have a say in the process because the Tribune Co. filed for Chapter 11 protection Dec. 8. The Cubs were not included in that filing.

Ricketts emerged as the finalist after receiving detailed financial data on the Cubs, Wrigley Field and a 25-percent stake in a regional sports TV network.

The Tribune Co. put the Cubs on the block on Opening Day in 2007 after announcing the company would be bought for $8.2 billion by a group led by Zell.

Cubs chairman Crane Kenney said in December he hoped the deal would be finalized in Spring Training and the new owners in place by Opening Day 2009.