TUCSON, Ariz. —— Dave Roberts never has played more than 139 games in any of his 11 professional seasons.

So the Padres know they must have a capable backup ready for the speedy, but slightly built leadoff man and center fielder. Roberts left the Padres' 4-3 loss to the Arizonan Diamondbacks at Tucson Electric Park on Saturday afternoon with what manager Bruce Bochy described as "a very slight tweak of the groin."

Bochy said Roberts will get today off and possibly Monday. With a scheduled day off Tuesday, that would give Roberts three days to fully recover.

"Hopefully, Dave's in the lineup 140 or so games and we really don't have a problem," Padres general manager Kevin Towers said. "Long term, if Dave went down, I'm not sure what we'd do."

That statement came after young center fielder Freddy Guzman was declared out for six weeks with a stress reaction and bruising of the throwing elbow. Realistically, Guzman won't be ready to play in a game until mid-May, at the earliest.

So Bochy has been holding an open tryout in center field.

Veteran utilityman Damian Jackson has made four appearances there but looked shaky Thursday against the White Sox. Veteran Mark Sweeney, better known as a pinch-hitter, made one start out there, as did Xavier Nady. Youngster Ben Johnson has filled in four times, and 2002 third-round draft pick Kennard Jones has been out there twice.

Veteran utilityman Eric Young has yet to play center this spring, although he made eight starts there last season while with the Texas Rangers.

"Short term, we'll probably use Young," Towers said. "We could use Nady in center or move Giles from right to center and play Nady in right. We have some options.

"Long term, if something bad happened, we might have to go get someone. But Ben Johnson has finally emerged. He might be the answer if we needed someone for a long stretch."

Johnson, who was acquired in a 2000 trade with the Cardinals that sent catcher Carlos Hernandez to St. Louis, hit .251 with 23 homers and 85 RBIs in 2004 in his third season at Double-A Mobile. He has been impressive this spring and is ticketed for Triple-A Portland.

"He'll be a phone call away," Towers said. "He's playing with confidence again. He's relaxed. I hope we don't have an emergency and need him, but he might be the guy."

First to four

Adam Eaton said he needed to get some work out of the stretch, and he definitely got that Saturday.

Eaton worked the first four innings of the Padres' loss to the Diamondbacks —— the first Padres pitcher to go four innings. He allowed three runs on 10 hits after not allowing a run in five previous spring innings.

"It was a super-dry day, and I was battling to get a grip on the ball," Eaton said. "I wanted to work on my curveball, but it was counter productive because I couldn't grip the ball.

"I'm working to get the loop out of the curve, tighten it, make it shorter. So I need to throw it in games, not just the bullpen."

Fick in the bullpen

Robert Fick, a left-handed hitting corner infielder, is working with the catchers to try to make himself more versatile. He even caught an inning against Seattle earlier this spring. He was drafted by the Tigers as a catcher out of Cal State Northridge.

Short hops

SS Khalil Greene was hitless in two at-bats Saturday and is 0-for-15 this spring. … Ramon Hernandez started behind the plate, making him the first Padres catcher to start back-to-back days. … 2B Josh Barfield had to leave Saturday's game after taking a one-hop ground ball in a sensitive area. … 1B Phil Nevin, who had Saturday off, has a four-game hitting streak, including three straight multihit games. Nevin is hitting .350 (7-for-20) this spring. … Today's scheduled B game with the Brewers was canceled.

Contact staff writer John Maffei at (760) 740-3547 or jmaffei@nctimes.com.