Tony Gwynn Jr. will remain Dodgers’ primary left fielder, Don Mattingly says

Juan Rivera worked out with the Dodgers for the first time at Chase Field on Thursday, but Manager Don Mattingly said his arrival wouldn’t affect Tony Gwynn Jr.’s status.

Gwynn will remain the primary left fielder.

“I think so, for the most part,” Mattingly said.

But Rivera, who was acquired from the Toronto Blue Jays for a player to be named or cash, can also play first base.

“I feel good at first base too,” Rivera said. “I feel better this year.”

The former Angels outfielder, who turned 33 this month, said he played plenty of innings at first base in the Venezuela winter league.

Mattingly said he envisions using Rivera in left field, right field and at first.

All three positions are occupied by left-handed hitters: Gwynn, Andre Ethier and James Loney, respectively. Rivera, who bats right-handed, was hitting .327 against left-handers for Toronto.

“I think it gives us a combination of ways to use him,” Mattingly said.

Despite Rivera’s uneven splits — he hit .219 against right-handers — Mattingly said he doesn’t think of Rivera as a platoon player. Rivera was with the Yankees from 2001 to 2003, when Mattingly was a special spring-training instructor for New York.

Rivera, who was with the Angels from 2005 to 2010, said he was glad to return to Southern California. He hit .287 with 25 home runs and 88 runs batted in for the Angels in 2009.

Rivera denied that he was in decline.

“I feel like the same hitter,” he said.

Barajas is back

Rod Barajas convinced the Dodgers that he is healthy enough to play in the three-game series against the Arizona Diamondbacks that starts Friday, prompting the team to clear a roster spot by sending A.J. Ellis to triple-A Albuquerque.

Barajas said the sprained right ankle that sidelined him for more than three weeks has healed, pointing to how he scored from first while on a rehabilitation assignment with Class-A Rancho Cucamonga.

But Barajas is as slow as Matt Kemp is fast. How did that happen?

“On a double down the right-field line,” he said.

Did the ball get stuck in the fence or something?

“Maybe I’m just fast,” Barajas said. “Maybe I picked up an extra step or two.”

Who will steal more bases over the rest of the season: Barajas or Kemp?

“He might get one or two more than me,” Barajas said.

He paused.

“One or two more every day,” he said.

When the joking subsided, Barajas talked about how he was pleased with the way he hit in four games for Rancho Cucamonga. He was seven for 18 with a home run, two doubles and four runs.

“I was completely comfortable,” said Barajas, noting that he sat out only four or five days of batting practice after getting injured June 18.

Barajas is batting .220 this season.

Mattingly said Barajas and Dioner Navarro would split catching duties.

dylan.hernandez@latimes.com