SCOTTSDALE, Ariz. — Bernhard Langer would have wrapped up the Charles Schwab Cup long ago under the old format. Instead, he has only a small lead and is one of five players who can take the season title with a victory Sunday in the PGA Tour Champions finale.

Still recovering from a left knee injury that forced him to withdrew from the playoff opener two weeks ago in California, Langer will open play in the Charles Schwab Cup Championship on Friday on Desert Mountain Club's Cochise Course. The 59-year-old German has a tour-high four victories and has wrapped up the season money title with $2,836,459.

"The season was fantastic," Langer said Thursday. "Just to have four wins, two majors, and what's even more impressive to me is actually not finishing outside the top 13 all year. That was my worst finish, 13th, which I've never done in my whole career. So that's pretty incredible."

He re-aggravated the knee injury at home doing routine spinning.

"It's better. It was pretty bad in L.A. when I pulled out," Langer said. "I couldn't really post up any weight on my left leg and follow through the way I wanted to follow through. I couldn't have walked that hilly golf course, either, because downhill was impossible for me to walk downhill.

"Last week, I was extremely careful. I played and I could play, but I had my caddie do a lot of the marking the ball, replacing the ball, lining it up. When it was downhill I went serpentine this way so I wouldn't put as much pressure on the knee. Might have to do a little bit of that this week, too, just to make sure I can finish the tournament, but right now it's not bad."

The season standings were re-set after the event last week in Virginia, with Langer's lead over Richmond winner Scott McCarron reduced from 935,657 to 200. The top five — Colin Montgomerie is third, followed by Joe Durant and Miguel Angel Jimenez — would win the season title with a victory Sunday no matter where the other players finish. The tournament winner will receive $440,000 and 2,000 points.

Langer won season titles in 2010, 2014 and 2015, but has never won the season-ending event.

"I love Desert Mountain, everything about it," Langer said. "The golf course is obviously in phenomenal shape. The people here are so kind and hospitable. Great sponsor with Schwab. Food is fantastic, locker room is great. Practice facility, it's all first class."

He played a practice round Thursday.

"The rough's a little bit up and some of the greens are really firming up," Langer said. "There were a few shots downwind that I couldn't stop on the green. It will be interesting to see what the wind does tomorrow, if it switches or how strong it is and all that. But it's a real test, no doubt about it."

Montgomerie pointed to the rough on the Jack Nicklaus-designed course.

"The overseeding has come in very strongly," Montgomerie said. "If you're trying to make birdies, you've got to hit the fairway. You can just about make a par if you're lucky from the rough, but you're not making birdies. So to win this, you've got to make birdies, which comes from the fairways."

The top 36 players in the standings qualified for the event, with the field reduced to 35 on Thursday when Tom Lehman withdrew because of an elbow injury. He withdraw after two rounds in the playoff opener at Sherwood and missed the event last week in Richmond.