The win ensures that the Yankees need not worry about scoreboard-watching on Wednesday; if they win their game against Boston, they will spill bubbly as division champions for the 13th time since 1996 and will also own home-field advantage throughout the first two rounds of the postseason.
"I think it's extremely important, because you want to be able to do that," manager Joe Girardi said. "If you win, you win the division -- that's the bottom line. We have a chance to have the best record, and that's the bottom line. That's a good feeling that you can control that."
New York logged 16 hits in the contest, but its lineup seemed to be stuck in neutral until the ninth, as Ibanez came off the bench and connected off Boston closer Andrew Bailey to tie the game.
"I had a 1-2 count and was just trying to put a short swing on it, get the fat part of the bat on it and not try to do too much," Ibanez said. "Fortunately it worked out."
The Yankees left the bases loaded in the ninth, but Rafael Soriano blanked the Red Sox in the 10th and Derek Lowe pitched two scoreless frames, standing in position for the win as Ibanez rolled his 11th career walk-off hit through the left side of the infield.
"This makes my season, because it's just one game left," said Francisco Cervelli, who tumbled home with the winning run after working a walk against left-hander Andrew Miller. "To have that chance, I can just go home really happy today."
Ibanez's ninth-inning shot came after Soriano served up a solo blast to James Loney, which appeared to be just an insurance run, offering Boston a 3-1 lead that it would not be able to protect.
"I threw it right down the middle," Bailey said. "There's nothing else to it. I left it [in the] middle and he did his job. There's nothing fun about going out there, letting guys run around the bases and do all that."
The Yankees would beg to differ; at the time, they appeared in danger of heading into the season's 162nd game deadlocked atop the division, with the out-of-town scoreboard relaying word of the Orioles' 1-0 victory over the Rays at Tropicana Field.
"I didn't sense frustration [in the dugout]," Girardi said. "They were business as usual. You keep giving yourself opportunities. Obviously there's a lot of excitement when Raul's ball goes out, and there's even more excitement when his ball goes through."
David Phelps turned in a solid 5 1/3-innings start, though he was shaky out of the gate, permitting hits to the first two batters -- Jacoby Ellsbury and Dustin Pedroia, headlining a lackluster Boston lineup -- and watching both score to give the Red Sox an immediate lead.
But the rookie settled in, proceeding scorelessly from there. Phelps allowed just three hits, walking two and striking out four in an 86-pitch outing.
"I've proven to myself that I can go out there and get through five," Phelps said. "At the beginning of the season, that was the big struggle. But I'm just comfortable in myself, comfortable in my team, knowing that if I go out there and pitch somewhat deep into the game, they're going to give me a chance to win."
The Yankees notched eight hits in five innings against Boston starter Jon Lester, but they were limited to just one run; of the unearned variety, as Curtis Granderson reached on a second-inning single that included a throwing error. Eduardo Nunez knocked the run in with an RBI single.
The Yankees' lineup was short-circuited in part by an 0-for-6 night from Mark Teixeira, who grounded into two inning-ending double plays and killed threats in the first, third and fifth innings. He also shattered his bat on a ninth-inning bases-loaded flyout.
"It's very frustrating, but I'm the happiest guy on the team right now," Teixeira said. "I guarantee you I'm the happiest guy on the team, because it could not have gone worse for me personally, but we won. I told Raul thank you about 100 times."
Teixeira wasn't alone in a Yankees clubhouse that, if everything proceeds according to plan, would be draped in champagne-soaked plastic covering in less than 24 hours. The Yankees have just one more bit of business to take care of.
"You know you're going to be in these situations when you come to play here," Ibanez said. "I feel really blessed to be a part of it, to be a part of this great tradition and legacy that is the Yankees. To get an opportunity like that and to be able to help the team win, it's definitely special."