DENVER (AP) The NL West-leading Colorado Rockies are off to a sizzling start with their top slugger in a slump.

Now even he's starting to heat up.

Nolan Arenado hit his first homer of the season to ignite a five-run sixth inning and the Rockies matched their best start in franchise history by holding on for a 7-6 win over the San Francisco Giants on Monday night.

The Rockies are 7-2 for the fifth time in team history. They also had that mark in 1995, '97, 2011 and '15.

''Our group is mentally in the right spot,'' Rockies manager Bud Black said.

That includes Arenado after his first extra-base hit of the season. This from a player who had 41 homers last season.

''There are a lot of pitchers that are going to have to pay for this,'' Black said of Arenado's slump.

On Monday, it was Johnny Cueto.

Arenado flew around the bases after sending one deep to left as his teammates applauded. Arenado and Black air fist-bumped near the dugout steps.

It was the 228th homer of Arenado's career, moving him past Carlos Gonzalez and into fourth place on the team's all-time list.

''You want to get off to a good start and I just don't,'' said Arenado, who tried out different bats in the cage before the game. ''I wish it wasn't like that, but it is for some reason. I've got to grind it out and find a way.''

That pretty much sums up his team as well.

Trailing 4-1 in the sixth, Arenado got things going with a two-run homer. The breakout inning also included an RBI single from Matt Kemp and a go-ahead single from David Dahl, with another run scoring on right fielder Alex Dickerson's errant throw.

Chris Owings added a much-needed insurance run with a solo homer in the eighth to make it 7-4.

It was a nerve-wracking ninth for the Rockies as the Giants scored two runs before newly appointed closer Jairo Diaz got the final out to earn his second save. He's stepping in for Wade Davis, who went on the injured list with a strained right shoulder.

Jeff Hoffman (1-0) pitched 1 2/3 scoreless innings in relief to earn the win.

Mike Yastrzemski, Chadwick Tromp and Dickerson went deep for the Giants, who started a season-long 10-game trip.

Cueto needed 29 pitches to escape the opening inning, but limited the damage to just an RBI single by Daniel Murphy. He settled into a groove before struggling in the sixth. Wandy Peralta (1-1) took the loss in relief after allowing three runs, two earned.

''Up to that point, I thought (Cueto) pitched in an excellent game,'' Giants manager Gabe Kapler said. ''And honestly, all you can ask of a great starting pitcher is to come into Coors Field and shut down the opposition for five innings. But he did a great job, put us in a position to win that game.''

Rockies starter Chi Chi Gonzalez lasted three innings, allowing three runs, in his season debut. It was a rare off outing by a Rockies starter. The group entered the day with a league-leading 2.00 ERA.

THIRTY SOMETHING

Count Kapler as thankful he has a 30-man roster for at least three of four games at Coors Field, which has been known to take a toll on a pitching staff. The rosters are tentatively scheduled to shrink to 28 on Thursday.

''Right now, especially at Coors, it's nice to have that added cushion, that extra pitching,'' Kapler said.

AROUND THE HORN

The Giants recalled lefty Andrew Suarez from their alternate training site. They optioned right-hander Andrew Triggs, who will be on the major league taxi squad. ... The Giants committed two errors.

TRAINER'S ROOM

Rockies: Reliever Scott Oberg (blood clots) will remain in Denver to be looked at by specialists. ''This is going to take a while to go through check lists, go through tests, go through a lot of different things to find out why this happened,'' Black said.

UP NEXT

Rockies ace German Marquez (1-1, 1.54) makes his first home start of the season Tuesday against San Francisco. He's 18-11 with a 5.01 ERA in his career at Coors Field. The Giants have yet to announce a starter.

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