Lehman won the season-long race for the Charles Schwab Cup title in a close battle with Mark Calcavecchia. Lehman finished slightly ahead and won the title and the $1 million annuity.
Calcavecchia needed to finish tied for second with only one other player and for Lehman to come in no better than a two-way tie for 12th.
Calcavecchia did his part with a two-under 69 that was good for a tie for second, but three others joined him. Loren Roberts, Michael Allen and Jay Haas tied for second with Calcavecchia, thus giving Lehman the Charles Schwab Cup title.
"This year-long event is so exciting. It turns out at the end always to have some kind of drama and this is some kind of drama," Lehman said in the trophy presentation. "To have this happen is a blessing beyond belief so I'm very thankful."
So too was Blake.
The third-round leader only managed an even-par 71 on Sunday, but it was enough for the two-stroke victory.
Blake won in Korea earlier this year, but before that, he hadn't made a trip to the winner's circle since 1991. Now, Blake is a two-time winner this season.
"It's real important," Blake said in a televised interview. "To finally get one win in Korea, then to back it up, sometimes it's harder to do that. And it's nice to have it happen so soon."
Blake began the final round two shots clear and broke into red figures for the first time Sunday with a short birdie putt at the par-five fourth. He missed the green at the par-three eighth and made bogey, but a 10-foot birdie putt at the ninth gave him back his two-shot lead.
Blake rolled in a 15-foot birdie putt at the 12th and was three in front, but trouble loomed. He bogeyed the 14th hole, but no player mounted a serious charge at Blake's lead.
Blake maintained a three-stroke cushion until he missed a short par putt at the 17th. He took a two-shot lead on to the tee box, then drove into a bunker. He hit his second fat from the sand and the ball landed in the rough short and left of the green.
From a fairly easy lie, Blake pitched six feet right of the flag. He needed two putts to win the championship, but only needed one.
"How can you go wrong winning on this golf course against this field," Blake asked on television.
Roberts (70), Allen (71) and Haas (71) joined Calcavecchia in second at six- under 278.
David Frost shot a one-over 72 and took sixth at minus-five.
American Presidents Cup captain Fred Couples heads to Australia Sunday night. He's playing the Australian Open next week before the Presidents Cup, but on Sunday, he posted a three-under 68 to tie for seventh.