''I do know this, if I win, I win,'' Lehman said about the Charles Schwab Cup points race. ''I know there are 30 really super players here. So, winning is not easy.''
Langer leads the standings for the $1 million annuity, 211 points ahead of Lehman. Roger Chapman is third, 657 behind Langer.
''I haven't really looked at the numbers to figure out what I have to do,'' Langer said. ''What I am trying to do is play a great four rounds of golf, and hopefully win the tournament. If I can play great this week, then hopefully I can win the Charles Schwab Cup. If I play rubbish, then I'm going to depend on help from others.''
The winner of the Charles Schwab Cup Championship, set to open Thursday at Desert Mountain's Cochise Course, will get 880 points, with players receiving two points for every $1,000 they earn in the $2.5 million event.
Langer and Lehman would win the season title with a victory, while Chapman needs a victory and some help to top the standings.
Langer could finish last and win if Lehman finishes in a two-way tie for fifth or worse and Chapman fails to win, while Lehman could finish as low as fifth and win if Langer finishes 22nd or worse and Chapman doesn't win.
For Chapman to win, the Englishman needs to win the tournament and have Langer finish in a two-way tie for sixth or worse and Lehman finish third or worse.
The tournament is the 50-and-over tour's first in Arizona since the 2002 Tradition at Superstition Mountain. The Tradition, a Champions Tour major, was played on the Jack Nicklaus-designed Cochise Course from 1989-2001.
''I think it's a second-shot course, so putting yourself in position will be very important,'' said Lehman, a Scottsdale resident who has two victories this year. ''Any time you play at home it's nice. Sleeping in my own bed is really nice.''
Langer also has two victories this season and leads the money list with $2,023,296. The German star is coming off a playoff loss to David Frost last week in AT&T Championship in San Antonio.
''If Tom should win and I finish whatever, second or third, my hat is off to him because he's played great golf under pressure and deserves to win,'' Langer said. ''He's had a great year and so has Roger Chapman. It's exciting that there are several players that have a chance and it comes down to the last tournament.''
Chapman has two major victories this year, winning the Senior PGA Championship in May and the U.S. Senior Open in July.
Fred Couples is making his first start since a back injury forced him to withdraw during the first round of the Boeing Classic in August in Washington. He won the Mississippi Gulf Resort Classic in March and the Senior British Open in July.
''I practiced yesterday for the first time since Seattle,'' Couples said. ''I don't even know think I gripped a club since then. I didn't really want to play golf and I thought the rest would help, and then I decided I would come here. The weather is perfect. ... I actually played pretty well today, which was surprising.''
Last year, Jay Don Blake won at TPC Harding Park in San Francisco.