Beltran expects to be back in the lineup again for Game 6 of the NLCS on Sunday, when the Cardinals again will attempt to punch their World Series ticket.
"Well, if I played today, why not?" Beltran said. "It will depend, after a long flight, getting there and continuing to follow the treatment and continuing to do what it takes to be in the lineup."
Beltran was a big question mark for the Cards all day, having exited Game 3 of the series in the first inning after spraining his left knee running out a double-play grounder and missing Game 4 entirely. He underwent an MRI scan on Wednesday that showed no structural damage, received treatment at Busch Stadium on Thursday and went off-site on Friday for acupuncture, seeing additional relief in the joint.
Beltran also revealed Friday that he was dealing with tight hamstrings.
But after several more hours of treatment on Friday afternoon, Beltran tested his legs in outfield running drills and deemed himself "good to go." He passed that message to Cardinals manager Mike Matheny, who finally posted a starting lineup at about 5:15 p.m. CT, just less than two hours before the first pitch.
"My concern was being able to run 100 percent, and I did that in the outfield," Beltran said before Game 5. "I still feel it, but it's not like yesterday or the day before."
Though he didn't appear in the Cards' win on Thursday, Beltran said afterward that his knee gave him little trouble when he tested it while hitting in the indoor batting cage. He pushed his knee through some light jogging, as well, then pushed it further in running drills in the outfield on Friday afternoon.
"We never saw anything structurally wrong, so the discussion was always about how much he could do with the discomfort that he was feeling," general manager John Mozeliak said. "He went out there and had a running test, and he went through all of it and felt capable of contributing. So he's in the lineup."
The biggest concern was whether Beltran's knee is strong enough to be able to handle duties in right field.
"I felt a little bit of pain in the knee, but I was good enough to play the game," he said afterward. "I just wanted to be out there. I felt OK. What can I say? Compared to how I felt [Thursday], today I felt like I was good to go."
Beltran's first-inning single off the Giants' Barry Zito was his 13th hit in the 2012 postseason, tied with teammate David Freese and San Francisco's Pablo Sandoval for the Major League lead.
Beltran will aim to add to that total in Game 6 of the series on Sunday night.
"We're still leading, 3-2, so we have to go in there and play hard, try to win one out of two," Beltran said. "Having a guy like [scheduled Game 6 starter Chris Carpenter] taking the mound, it's going to be encouraging for us. Hopefully, we can score a lot of runs for him and we can win this."