Arizona Diamondbacks outfielder A.J. Pollock has an avulsion fracture in his left thumb, D-backs manager Torey Lovullo said Tuesday.

Lovullo said Pollock is expected to be out at least four weeks and up to potentially eight.

“We know that A.J.’s going to do everything he possibly can to get back as quickly as possible,” Lovullo said. “Everybody heals differently. Obviously that’s a big range there, so we’re going to remain as optimistic as possible.”

Pollock was placed on the 10-day disabled list. The D-backs called up Christian Walker to take his place on the roster.

The D-backs lost their center fielder Monday night when, in the ninth inning, Pollock attempted to make a diving grab on a liner hit by Milwaukee Brewers pinch hitter Tyler Saladino, who ended up scoring on an inside-the-park home run.

Lovullo said he didn’t think Pollock should have refrained from diving for the ball.

“We never ask our athletes to back down from any challenge, from any play, and that’s what good teammates do. They feel like they can go out there and make a play,” Lovullo said. “We never, ever fault our guys for getting after it.”

Pollock leads Arizona in average (.293), home runs (11), RBI (33) and hits (44). The National League Player of the Month for April leads the NL in slugging percentage (.620) and was in the NL’s top-five players in producing home runs, RBI, extra-base hits, total bases and Wins Above Replacement.

Arizona will likely turn to veteran outfielder Jarrod Dyson and utility man Chris Owings to play increased innings in the outfield.

Owings, though primarily an infielder, played 49 games at center field in 2016 when Pollock was injured, which was the year before Lovullo became manager.

“A lot of discussion last night about Chris,” Lovullo said. “It was strongly recommended to me that he would be able to by several people that have seen him.”

Walker will return to the major league team after going 2-for-15 as a reserve so far this season. With Triple-A Reno in 13 games this season, the first baseman is slashing .286/.288/.531 with half of his 14 hits of the multi-base variety.

The Associated Press contributed to this story.

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