The All-Star second baseman hit a pair of two-run homers to back a solid effort by David Phelps, and New York beat the Toronto Blue Jays for the ninth straight time at Yankee Stadium, 7-2 Saturday.
"I'm glad that's not a moving part," Girardi said. "He's not someone you can replace."
Phelps (2-2) struck out eight while allowing one run in a season-high seven innings, helping New York beat the Blue Jays for the eighth time in nine games this season.
Cano connected off Brandon Morrow with two outs in the third after Brett Gardner drove in the first run of the game with an RBI single. Cano also hit one off Morrow (1-3) with two away in the fifth, a shot that gave him his second multihomer game of the year. He has 12 such games for his career.
"I felt like I threw a lot better than what the scoreboard indicated," Morrow said, "but just that, you know, New York's Robinson Cano, he was the whole ballgame."
Travis Hafner returned to the Yankees' lineup after missing five games because of right shoulder inflammation and hit a two-run homer in the eighth inning.
The AL East's top team will send ace CC Sabathia to the mound Sunday with a chance to complete its second sweep of Toronto in the Bronx in three weeks. The Yankees took four straight from April 25-28. The Blue Jays counter with NL Cy Young Award winner R.A. Dickey.
Toronto has lost 23 of its last 28 games at Yankee Stadium.
"Yankee Stadium is always a tough place to play, regardless," Blue Jays manager John Gibbons said. "They've taken it to us pretty good here."
Making his fourth start in place of the injured Ivan Nova, Phelps was at his best with runners on base. In the first, he walked Jose Bautista and Edwin Encarnacion but picked Bautista off second base and struck out J.P. Arencibia to end the inning. With runners on first and second in the third, Phelps got Melky Cabrera to ground into a double play. After again walking Bautista, he struck out Encarnacion with a high fastball for the third out.
The Blue Jays cut the lead to 3-1 in the fourth. After Adam Lind had the first of his two doubles, Colby Rasmus hit a sharp liner that Curtis Granderson, playing right field for the first time in his big league career, got spun around on and Lind scored. But Phelps struck out Maicer Izturis to limit the damage.
"I was making pitches when I needed to," Phelps said. "I was all over the place today."
Phelps was greeted on the field just in front of the dugout with a handshake from Girardi after a 1-2-3 seventh. Phelps yielded six hits and walked three.
David Robertson gave up Encarnacion's 12th homer in a rainy eighth inning.
Morrow had his start pushed back from Wednesday because of neck and back tightness, and the rest appeared to have served him well early. He retired six in a row before Jayson Nix singled to start the third.
With two outs, Gardner singled to centre field and third base coach Rob Thomson signalled Nix home with a feverish windmill of his right arm. Nix slid in before the throw arrived.
Cano then sent the next pitch on the shortest possible journey out of the ballpark, just clearing the fence down the right-field line. Cano hit his 12th of the year in the fifth with a no-doubter to right-centre, driving in Austin Romine, who singled.
"That was a good game," Cano said.
Morrow was lifted after throwing 75 pitches in five innings. He allowed seven hits and five runs.
NOTES: Yankees owner Hal Steinbrenner, at the stadium for fan photo day, said he was pleasantly surprised but "not shocked" by New York's early success, considering all the injuries. ... New York acquired INF Reid Brignac from Colorado for cash. He was recently designated for assignment by the Rockies. ... Gibbons said LHP J.A. Happ (skull fracture, knee) is still sidelined because of the knee injury he sustained when he fell to the turf after being hit in the head by a line drive and is not near pitching again. Gibbons said Happ's head is fine. ... Blue Jays RHP Josh Johnson (triceps) will make his first rehab start on Monday for Class-A Dunedin. ... Cabrera doubled for the fifth straight game, a career high.