Abreu worked out a nine-pitch walk that loaded the bases in the fourth inning, and Williams followed with a tiebreaking, three-run double that led New York over the Toronto Blue Jays 5-1 Tuesday night.
"We're in a very good situation right now, coming into the last two months of the season," Williams said.
With their sixth win in seven games, the Yankees (62-41) moved into the AL East lead for the first time since before play on June 18, leading the Boston Red Sox (63-42) in percentage by .602 to .600.
"The only thing that means is we don't have to worry about other teams," Derek Jeter said. "Now, if we play better than the rest of the division, we'll win."
Abreu, acquired from Philadelphia on Sunday, batted fifth and started in right field. He went 0-for-3, grounding out in the second, flying out in the sixth and grounding out in the seventh.
With runners on second and third in the fourth inning following Alex Rodriguez's tying double on a 3-0 pitch, Abreu came up with none out against A.J. Burnett (2-5). Abreu fell behind in the count 0-2, then checked his swing on a close pitch and took two more balls. He fouled off three pitches before checking his swing on ball four.
"I guess the umpire saw me out there, so I think they know that sometimes I take close pitches," Abreu said.
Toronto wasn't happy with the check swing calls by third base umpire Ed Hickox.
"They were able to lay off some very tough pitches with two strikes, and those calls went their way," catcher Gregg Zaun said.
After Jorge Posada struck out, Williams drove a pitch to the opposite-field gap over diving left fielder Reed Johnson for his 442nd double, tying Don Mattingly for second on the Yankees' career list behind Lou Gehrig (535). Williams, who re-signed with the Yankees to be a part-time player, has 46 RBI this season.
"He basically understands that he's a role player right now," manager Joe Torre said. "He's never been promised a starting job."
New York traded for Abreu to play right in the absence of Gary Sheffield, out since wrist surgery in June. With Sheffield and left fielder Hideki Matsui (broken wrist) hoping to return in September, Sheffield said before the game that he wouldn't mind a shift to first base when he gets back.
Abreu's arrival, combined with the acquisition of first baseman-right fielder Craig Wilson, is likely to cut Williams' playing time.
"I kidded with him, saying, `You're probably not going to play anymore,"' Torre said. "Then I basically told him he'd DH sometimes and play center field when Johnny needs a break."
Williams was the designated hitter Tuesday and said he's willing to fill any role.
"When everybody got hurt, it was a bonus for me," he said. "Hopefully, Joe will have enough confidence in me to throw me out there in certain situations."
Abreu said cheers from the crowd of 52,237 made him feel at home. He had a busy day in right field, catching six fly balls, including a warning-track drive by Frank Catalanotto with two on and two outs in the seventh.
Jaret Wright (7-6) won for the first time in three starts, allowing an RBI double in the second to No. 9 hitter John McDonald. Wright lasted five innings and 103 pitches on a hot, humid night, giving up five hits, striking out five and walking one.
Ron Villone, Scott Proctor and Kyle Farnsworth followed with two-hit relief. Rodriguez padded the lead with an RBI grounder in the seventh off Brandon League.
Burnett, who had been 2-0 against the Yankees, allowed four hits but left after a 40-pitch fourth inning pushed his pitch count to 86. He has lost four of his last five decisions.
"He's really pitched pretty good for us, better than his record indicates," Toronto manager John Gibbons said. "But he's like anyone else, he's got to throw strikes."
- The Yankees limited use of their out-of-town scoreboard, video board and televisions in the stadium to preserve energy during the heat wave. The gametime temperature was 96.
- Toronto has lost five of six.
- Jason Giambi started at first base but left after six innings because his right leg cramped up. "I'm not built for this type of weather," he said.
- The Yankees are 21 games over .500 for the first time this season.