BOSTON – One of Bobby Valentine’s first acts as Red Sox manager was to visit David Ortiz in the Dominican Republic and let him know how important it was to keep him on the team.

Now everybody is seeing that.

Ortiz, who was a free agent in the offseason, is off to one of the best starts of his career. On Sunday, the slugging designated hitter doubled home the go-ahead run for his seventh consecutive hit, and Boston won its third straight game over the Tampa Bay Rays, 6-4.

“I definitely wanted to let him know that the new guy really wanted him,” said Valentine, who was named manager Dec. 1. “I think that’s basically all I said, that I always appreciated watching him from afar and I know how important he is to any team. And I wanted him on mine.”

Ortiz agreed to a one-year, $14.575 million contract on Feb. 13 and brought a greater desire to play a leadership role.

“The best way to be a leader is come to the ballpark, prepare and be a professional, and we all know that’s what Papi is,” Boston’s Adrian Gonzalez said.

One thing that hasn’t changed is the left-handed Ortiz’s ability to hit lefties. Last season, he batted .329 against lefties and .298 against righties. He went 3 for 4 on Sunday, with all the hits against left-hander Matt Moore (0-1).

“Lefties are hittable, too. It all depends (on) what your mind-set is,” Ortiz said. “They throw the ball over the plate just like righties.”

Boston, on a tear since a season-opening 1-5 trip, can complete a series sweep in today’s traditional Patriots Day game that starts at 11:05 a.m. Last year, the Red Sox were 2-7 at home against the Rays.

“When you’re playing a Tampa team that’s touted to win 100 games in our division, you must feel pretty good about it when you come out fighting like we did,” Valentine said.

Ortiz is 16 for 36 in nine games this season.

“That’s pretty impressive,” Tampa Bay’s Carlos Pena said. “It seems like he’s squaring the ball up every time he’s up.”

Ortiz has struggled in recent years in April. He had 20 hits in 22 games in 2009, eight in 16 games in 2010, and 23 in 25 games in 2011.

With the score tied 4-all in the sixth inning, he doubled home Kevin Youkilis, who had walked.

Ortiz went 4 for 5 with a homer and five RBI in Saturday’s 13-5 win. Then he doubled, singled and doubled in his first three at-bats Sunday before grounding out to first to end the seventh.

Also in the seventh, Mike Aviles hit his second solo homer in two days from the leadoff spot. He moved there for the first time this season on Saturday when Jacoby Ellsbury went on the 15-day disabled list with a partially separated right shoulder.

“Matt got us deep into the game,” Rays Manager Joe Maddon said. “I thought he was still in good shape out there up until the end.

“They’re just really hot right now.”

Vicente Padilla (1-0) pitched 12/3 scoreless innings after Felix Doubront left the game following Luke Scott’s leadoff homer that tied it in the sixth.

Alfredo Aceves pitched the ninth for his second save in three opportunities.

Moore gave up six runs on eight hits in 61/3 innings in the third regular-season start of his career.

The Red Sox scored first for the first time in the series, getting three runs in the second. Youkilis singled, Ortiz walked and Cody Ross hit his second homer in two days.

They made it 4-0 in the fourth on Kelly Shoppach’s RBI double.

Doubront, making just his fifth major league start, allowed four hits in four scoreless innings before struggling in the fifth, when he allowed three runs.

Chris Gimenez singled, Desmond Jennings doubled, and Pena doubled home two runs. Evan Longoria made it 4-3 with a ground-rule double.

NOTES: Ralph Branca, Valentine’s father-in-law, threw out the ceremonial first pitch on the 65th anniversary of Jackie Robinson breaking baseball’s color barrier. Branca, a right-handed pitcher, is the last surviving member of that Brooklyn Dodgers team in 1947. … The Red Sox called up outfielder Jason Repko and utility player Nate Spears from Pawtucket, optioned outfielder Che-Hsuan Lin to the Triple-A team and designated right-hander Michael Bowden and catcher Luis Exposito for assignment.