ANAHEIM -- Gary Matthews was held out of Saturday's lineup against the Red Sox, and he will be sidelined indefinitely as he rehabs from a small tear to the patellar tendon in his left knee.

The Angels outfielder met with team orthopedist Dr. Lewis Yocum to discuss the results of an MRI taken on his ailing left knee, and the exam revealed a tear but no other structural damage to ligaments or surrounding cartilage.

Out since Sunday, Matthews was not immediately sent to the disabled list, but he was uncertain when he would be able to return to the field. One thing he ruled out was surgery, unless the procedure is a last-ditch effort to get him back into the lineup.

"The plan for now is to continue to treat it and strengthen it," Matthews said. "We'll probably be a little more aggressive with our treatment, maybe a little bit different medication and try to figure a way to make it feel better and manage it until the offseason."

Matthews has suffered with patellar tendinitis since last September, when he missed the Angels' first-round postseason loss to the Red Sox. The 33-year-old is currently hitting .235 with seven homers and 34 RBIs while posting a .310 on-base percentage.

"I have my good days and I have my bad days, and you get to the point where you're not getting the results that you want," said Matthews, who feels pain particularly when he bats from the left side. "Now we know what we've got."

Matthews signed a five-year, $50 million deal in the offseason prior to 2007 to play center field. He held that position last season, but he has been supplanted by Torii Hunter, whom the Angels signed to a five-year deal in November.

Through 89 games this season, Matthews has rotated through all three outfield slots and designated hitter. If the Angels opt to place him on the DL, Matthews would be nearly halfway through the minimum downtime.

"It is something that has been bothering him since last season," Angels general manager Tony Reagins said.

The recent surge of Juan Rivera, who has three homers and eight RBIs in nine starts in July, has allowed the Angels to take a slower approach with Matthews.

"When you have surgery, you're talking four to six months, and I've not even discussed that; I wouldn't entertain it," said Matthews, adding that Yocum did not recommend surgery. "Hopefully, in the offseason, I can stay healthy and it continues to heal, and I can get better."