Brian McCann and Carlos Beltran had two-out RBIs for the Yankees, who began a 10-game homestand by winning the opener of an interleague series against a National League contender. New York, with a major league-high 40 home games after the All-Star break, improved to 19-23 at Yankee Stadium.
Dellin Betances struck out three in 1 2-3 perfect innings, and David Robertson got three outs for his 24th save in 26 chances.
Phelps (4-4) gave up three runs -- two earned -- and six hits in 6 1-3 innings against a lineup missing injured thumpers Joey Votto and Brandon Phillips. The right-hander struck out seven and walked one for his first win since June 19 against Toronto, which preceded four straight no-decisions.
It was the kind of performance New York needs from the unheralded fill-ins in its injury-ravaged rotation. Before the game, general manager Brian Cashman announced that left-hander CC Sabathia is scheduled for surgery on his right knee Wednesday -- ending any hope of him returning this year.
Brayan Pena, subbing for Votto at first base, homered twice for the Reds. Mike Leake (7-8) allowed four runs and eight hits in seven innings.
With the score tied 2-all, Derek Jeter singled to start the fifth, and Ellsbury lined a 1-1 pitch to the short porch in right field for his seventh home run.
Brett Gardner was hit on the left foot by Leake's third pitch. Shaken up a bit, he was checked by manager Joe Girardi and a trainer before remaining in the game.
Gardner stole second and scored on McCann's two-out double.
Jeter's leadoff single in the third deflected off third baseman Todd Frazier. Ellsbury also singled before Beltran, just activated from the seven-day concussion list, came through with a two-out single.
Pena connected off Phelps to start the third and seventh for his first career multihomer game.
Cincinnati tied it at 2 in the fourth, capitalizing on errors by Brian Roberts at second base and Jeter at shortstop. Devin Mesoraco had an RBI grounder, but Phelps prevented further damage.
NOTES: Cincinnati will start All-Star pitchers in the final two games of the series. RHP Alfredo Simon (12-3, 2.70 ERA) goes Saturday, when RHP Brandon McCarthy makes his home debut for the Yankees. RHP Johnny Cueto (10-6, 2.13) faces New York RHP Hiroki Kuroda (6-6, 4.10) on Sunday. ... Votto is eligible to come off the disabled list Monday, but there is no timetable for his return from a strained muscle above his left knee. ... Skip Schumaker hopes to return from a concussion this weekend. ... Jeter made his 2,610th career start at shortstop, passing Omar Vizquel for the most in major league history. ... The Yankees announced they will honor Jeter during a ceremony before their Sept. 7 home game against Kansas City. Jeter is retiring after this season. ... Beltran also beat the shift with a check-swing double down the third-base line. ... It was the 15th anniversary of David Cone's perfect game at Yankee Stadium.