CHICAGO (Reuters) - The Chicago White Sox eased to a 9-4 victory over Oakland on Thursday, condemning the Athletics to a 10th consecutive loss just hours after Bob Melvin replaced fired manager Bob Geren on an interim basis.

Melvin's changes to the batting order led to an early 1-0 lead for the visitors, but Chicago tapped Oakland starter Trevor Cahill for six runs, including a two-run homer by Adam Dunn, to grab control.

Hideki Matsui's two-run blast in the seventh inning narrowed Chicago's lead to 6-3 before the White Sox made sure of victory with three more runs in the eighth. Oakland added one more run in the ninth.

"There's just so much going on, on a day like this," Melvin told reporters. "It just seems like the baseball is secondary, and once you get to the game it's a bit of a relief, that a game is going on.

"There were travel issues not only with me but with players last night... meetings here and there, and you've got to get your feet wet in a new uniform. I've never done it mid-season before, either, so it's a little different."

Earlier on Thursday, Oakland general manager Billy Beane said in a statement that Melvin would serve as temporary manager for the rest of the season and the changeover was effective immediately.

"Bob Geren has been relieved of his duties as manager and former Major League manager Bob Melvin has been named interim manager for the remainder of the 2011 season," Beane said.

The slumping Athletics have had an indifferent start to the season and now sit bottom of the American League West standings with a 27-37 record.

Geren, 47, who had compiled a 334-376 record in his four completed seasons with the A's, was in the final year of his contract but facing increasing criticism over the team's poor performances and his managerial style.

Melvin, 49, posted a 493-508 record in seven previous seasons as a Major League manager. He led the Seattle Mariners from 2003-2004 and the Arizona Diamondbacks from 2005-2009.

The Athletics have won the World Series four times since they moved from Kansas to California in 1968. Their most recent championship was in 1989 and their last appearance in the World Series was 1990.

(Reporting by Gene Cherry in Raleigh; Editing by John O'Brien)