The 32-year-old Lyle said his legs felt heavy but he would draw on his "fighting instinct" to finish the weekend.
"If I have to crawl those last 18 holes, I'm crawling them," Lyle said. "Nothing's going to stop me from finishing."
Lyle, then a regular on the U.S. PGA Tour, was diagnosed with leukemia in March 2012 just before the birth of daughter Lusi. Lyle's wife, Briony, became pregnant despite medical advice that Lyle's first bout of cancer and the resulting chemotherapy would leave him sterile.
He has a medical exemption to return to the U.S. PGA Tour whenever he feels he's ready. But Lyle said Friday he won't be rushing back to the U.S. until he knows he's physically capable "I don't want to waste the medical starts that I have."
Otherwise, he was enthused about his return.
"I've done it; I've come here and achieved the biggest goal I've set myself for the week and that was to play four rounds of golf," Lyle said. "I couldn't be happier than what I am."
Scott said he and the other Australian golfers were all hoping Lyle would make the weekend.
"It's phenomenal, he's a beauty," Scott said. "I'm so happy for him. To see him finish 1-over, it's great. We love having him back."