"He's ready," Leyland said. "He feels pretty good. I don't think it will be any kind of a drawback."
Avila injured the knee in a collision at home plate with David Ross, the Red Sox catcher who was trying to score on a ground ball with the infield in. Avila stayed in the game for two more innings before coming out. He was replaced by Brayan Pena.
Avila said before Game 6 that he took medication to calm the inflammation and felt significant improvement.
"Compared to two days ago, I'm good," he said.
Avila said the injury is comparable to the patellar issues he suffered down the stretch during the 2011 season, eventually leading to both knees bothering him during the playoffs. He struggled to hit that postseason because he couldn't generate enough power in his swing through his legs.
Leyland's main concern is Avila starting the game and having to come out because of the knee.
"If you can't go, that's all right," Leyland said. "The one thing you don't want to have is have him start the game and then take him out in the second or third inning."
The knee is the only issue with Avila at this point. Leyland confirmed that Avila underwent tests for a possible concussion Thursday after taking a foul tip off the front of his mask, but tested fine.
"They gave him all the symptoms tests without going to the hospital," Leyland said.
Leyland also said Doug Fister could be available in relief Saturday -- and Sunday, if the series goes seven games. Fister started Game 4 on Wednesday night.
"But if we need a long man, we're in trouble," Leyland said.
T.R. Sullivan is a reporter for MLB.com. Read his blog, Postcards from Elysian Fields, and follow him on Twitter @Sullivan_Ranger. Jason Beck is a reporter for MLB.com. Read Beck's Blog and follow him on Twitter @beckjason. This story was not subject to the approval of Major League Baseball or its clubs.