"It's just sore. I'll be all right," Lackey said. "It still doesn't look great."
Lackey planned to get treatment later in the afternoon.
"Probably everything they've got in there," he laughed.
Lackey (7-9) pitched six-plus innings against the Astros. He threw 113 pitches, giving up both Houston runs on eight hits and striking out 10, his second most strikeouts of the season. He was pulled after giving up a leadoff double and bunt single in the seventh.
"He was a little slow," manager John Farrell said of seeing Lackey walk Tuesday. "He'll be off the foot today. He's got an extra day of rest."
Knuckleballer Steven Wright made his first Major League start Tuesday night for the Red Sox, pushing everybody in the rotation back a day. Lackey isn't schedule to pitch again until Sunday in Kansas City.
Farrell wasn't sure if Lackey would be able to stay in the game Monday night with the ankle injury.
"If we saw anything different [in his delivery], 'Don't fight us, because you're coming out of that game,'" Farrell said he told Lackey. "We're not going to take any chances. The treatment he gets the next few days is going to be important.
"I think he did a great job. He pitched with it -- and pitched pretty darn well."
Lackey downplayed any talk about his injury being serious.
"I've hurt my elbow worse than that," he said. "[My ankle] will be fine."
Gene Duffey is a contributor to MLB.com.
This story was not subject to the approval of Major League Baseball or its clubs.