CHICAGO -- Kyle Hendricks laid the foundation, the bats came alive and the Cubs’ bullpen hung on in its first test since closer Craig Kimbrel went on the injured list. It was a bit of an adventure, but the result was the same it has been since the Cubs returned home last week.

Hendricks allowed just one hit and struck out five over 6 1/3 innings, Ian Happ hit a tiebreaking homer, Javier Báez went deep twice and David Phelps earned his first save of the season as the Cubs won their fourth straight game, 6-5, over the Athletics on Monday night at Wrigley Field.

• Box score

“Tough night, but we won it,” manager Joe Maddon said. “I’m going to go home with that.”

Happ’s pinch-hit solo shot traveled 474 feet and sparked a four-run seventh inning that gave the Cubs a 6-2 lead. Nicholas Castellanos, who hit his first home run in a Cubs uniform in the first inning, added an RBI double and Baez’s second homer capped the rally as the Cubs got to A’s reliever Blake Treinen.

The A’s rallied to make it a one-run game in the eighth as Cubs reliever Steve Cishek allowed a double to Jurickson Profar before surrendering back-to-back home runs to pinch-hitter Nick Martini and Marcus Semien.

But the Cubs’ bullpen -- without the injured Pedro Strop and Kimbrel, who was placed on the 10-day injured list before Monday’s game -- was able to close out the victory. Brandon Kintzler relieved Cishek and got Mark Canha to ground out to end the eighth with the potential tying run on third, but there was more drama in the ninth.

Kintzler left the game with discomfort in his right pectoral, which forced Maddon to extend the bullpen farther than he hoped. Kyle Ryan quickly recorded two outs in the ninth before allowing a walk and a single. But Phelps got Semien to fly out to the warning track in left to end the game.

With Kimbrel out, Maddon said it will be closer by committee, which Hendricks said he and his fellow starters are fine with until Strop and Kimbrel can return.

“I think [the closer] is whoever is available,” said Hendricks, who threw 104 pitches on Monday night. “It’s probably how it will go for a while now. Every guy down there has the capability of getting big outs, so I don’t think we’re worried about it.”

Semien also had the only hit off Hendricks, a two-run homer in the third inning that followed the first walk issued by a Cubs starter in seven games. Despite the rare free pass, Hendricks said he felt his command was on-point, and the addition of an effective curveball kept the A’s off balance.

“Kyle was Kyle,” Maddon said. “That’s what we’ve come to expect from him.”

Baez’s two home runs came on a night when he celebrated his five-year anniversary of making his Major League debut. He celebrated in style.

“I’m pretty excited to still be here, healthy,” Baez said. “I’ve been through a lot, but I’ve been trying to learn something every day.”

With the game tied at 2 in the seventh, Hendricks departed after allowing a one-out walk to Canha. Reliever Rowan Wick got Stephen Piscotty to ground into a double play to end the threat, and the Cubs’ offense went to work a half-inning later.

Starting with Castellanos, the Cubs’ ability to produce throughout the lineup has been key during a homestand that has started with four straight victories. But with All-Star catcher Willson Contreras out for four weeks with a hamstring injury, the Cubs will need to rely on a complete cast of characters.

“It’s hard, but we have to fight through it,” Baez said.