The Portland Sea Dogs got timely hits in Thursday night’s season opening 7-5 win over the Binghamton Rumble Ponies, but the most encouraging sign for Red Sox fans was the work of starting pitcher Garrett Whitlock.

Making a rehab start before he returns to Boston’s rotation next week, Whitlock pitched six strong innings, allowing just one hit while striking our eight and walking one in front of 6,478 fans at Hadlock Field.

It wasn’t a perfect night for the Sea Dogs, by any means. Handed a six-run lead with three innings to play, Portland’s bullpen made it close, allowing four runs in the top of the seventh.

The only hit Whitlock surrendered was a home run to Luke Ritter leading off the fifth, and came after he sat a while, as the Sea Dogs batted around the order in the bottom of the fourth. After that, Whitlock settled down, retiring the final six hitters he faced, striking out three of them.

Whitlock threw 81 pitches, 56 for strikes. His fastball was consistently in the low 90s. The one mistake pitch to Ritter was a two-seam fastball that caught too much of the middle of the plate, Whitlock said.

“It was pretty good. Obviously, I would like to take one pitch back. Other than that, though, a decent outing,” Whitlock said. “I’m feeling healthy. That’s the biggest thing, and ready to go.”

This was Whitlock’s second rehab start, and second Opening Day start in less than a week. He started for Triple-A Worcester last Friday and allowed one earned run and six hits over four innings, striking out six and walking one while throwing 70 pitches. Whitlock planned to drive back to Boston after Thursday’s game and fly to Detroit to join the Red Sox.

Whitlock pitched at Hadlock Field last season on a rehab assignment, and with Trenton when he was in the New York Yankees system.

“It was great coming back. I loved pitching here while I was with Trenton,” Whitlock said. “It’s always a great crowd, great atmosphere. I really enjoy pitching here in Portland.”

The Sea Dogs did much of their damage with two outs, including four of the five runs scored in the bottom of the fourth inning. Tyler McDonough’s two-out, two-run home run, a 424-foot shot to right field, pushed Portland’s lead to 4-0. After Phillip Sikes and Nick Yorke took back-to-back walks, Ceddanne Rafaela dropped a single just fair down the left-field line, scoring both Sikes and Yorke for a 6-0 lead.

In the bottom of the fifth, Portland added another two-out run on Christian Koss’ RBI single that drove in Alex Binelas.

The game tightened up after Whitlock left. Lefty Brendan Cellucci started the seventh and walked four batters, only avoiding walking in a run because he picked Brandon McIlwain off first base. With two outs and the bases loaded, Ryan Miller came on and surrendered a grand slam to right field by Matt Rudick.

Miller pitched a 1-2-3 eighth, however, and Luis Guerrero worked the ninth to earn the save. After walking leadoff hitter JT Schwartz, Guerrero got three quick outs, ending the game with Hayden Senger’s soft line drive to Koss at shortstop.

Portland took a 1-0 lead when Phillip Sikes led off the bottom of the third inning with a 437-foot home run to center field.

Binghamton starting pitcher Troy Miller lasted just 3 2/3 innings, allowing three runs on three hits and three walks while striking out four.

As is tradition for big leaguers making a rehab trip to the minors, Whitlock bought the postgame clubhouse spread for the Sea Dogs – hibachi and sushi from Kon Asian Bistro.

“That’s what I got last year when I was here. I’m a big hibachi fan, so I thought the boys might enjoy it,” Whitlock said.

Staff Writer Glenn Jordan contributed to this story.