"I thought I was going to have to jump," Matthews said, "and at the last second I contracted my quad pretty strongly.
"They had me do some movement and exercises and said, `If it's not attached to the bone, you wouldn't be standing here,' I'm going to go with the team to Oakland, and as long as they tell me it's attached and structurally sound, I'll take their word.
"I'm hoping I'll be available a week from now. You work so hard and endure a full season of 162 games, you want to play in the playoffs, have that opportunity."
Matthews was in his fifth start after missing 10 games with a sprained right ankle sustained on Sept. 11 in Baltimore running the bases.
The knee problem surfaced in Cincinnati in mid-June when Matthews leaped to try to flag down a home run by Ken Griffey Jr. He re-injured it in a first-base collision with Red Sox first baseman Kevin Youkilis in early August.
"Gary's had a little tendinitis off and on with the patellar tendon," Angels manager Mike Scioscia said. "He just tweaked it a little."
The field was wet, rains having delayed its start, but neither Matthews nor Scioscia thought that was a factor.
"His timing might have been a little off going up," Scioscia said. "It looked like he landed a little awkwardly.
Asked if it's a serious concern, Scioscia said: "Not right now there isn't. We'll certainly read it every day and go through the weekend. Our hope is to get him out there and take it one step at a time."
Matthews has played 140 games this season, with 133 starts in center, where his defense has been Gold Glove-caliber. Moving up and down the lineup offensively, he has provided power (18 homers) and speed (18 steals), his average tumbling to .252 with a late-season slump related to several injuries.
"Obviously, it may not be 100 percent," Matthews said, referring to the prospect of playing in the postseason at less than his best. "But I'm going to get as close as I can.
"This time of year, no one's 100 percent. Hopefully, the longer we go, the better I'll feel."
Matthews was on the ground for a while after his awkward landing, but he got up and walked off the field on his own power. He was replaced in the top of the second inning by pinch-hitter Nathan Haynes, who took Matthews' spot in center.
Hoping to regain his timing for the postseason, he has gone hitless in his past 17 at-bats. But he hit several balls hard in this series and felt he was making progress with his timing in the batter's box.
"I was just starting to get comfortable again in the batter's box," Matthews said. "I didn't get any hits here, but I had some good at-bats, worked some counts.
"When you're having problems physically, you've got to work harder on the mental aspects, on visualizing things. Hopefully, that will help me when I come back."