"That's one of the highlights of [Monday's] game," Piniella said. "He made a couple real nice plays and felt real comfortable out there. We'll continue to play him there from time to time. It gives us different options, if we chose."
Fontenot is competing with Jeff Baker for regular playing time at second base, but if he can also handle shortstop, it will help the Cubs make decisions regarding their bench. They may be able to have a more offensive-oriented player such as Chad Tracy or Kevin Millar as an extra man instead of worrying about making sure there is enough defense.
Monday wasn't the first time Fontenot played shortstop. He played there for the first month of 2007 when he was at Triple-A Iowa. Last season, when he wasn't playing second, Fontenot would take grounders at short, as well.
"I enjoy moving around," Fontenot said Tuesday. "It's fun to do that. Most of the time, if I'm not starting, I'm probably at shortstop. It breaks up the monotony."
On Tuesday against the Milwaukee Brewers, he was back at second base, part of what could be the Cubs' Opening Day lineup. Ryan Theriot was leading off, followed by Kosuke Fukudome, Derrek Lee, Aramis Ramirez, Marlon Byrd, Alfonso Soriano, Fontenot, and Geovany Soto.
"I said that to [bench coach] Alan [Trammell]," Piniella said. "I said, 'Right now, this would be our Opening Day lineup.' And let's wait and see what happens at second base. This is as close as you want to get to it."
Fontenot had been slowed by a sore right shoulder, which he injured last Thursday in the Cubs' first Cactus League game when he took a tumble at third base. He hasn't had any problems since.
"I completely forgot about it," he said.
The Athletics didn't waste any time testing Fontenot's throwing ability, as he fielded several grounders in the early going.
"They tried to get me right off the bat," Fontenot said. "That's usually what happens is you get out there and someone hits a missile at you. It was just good to get out on the field. I hadn't played in a few days."
The throw from short compared with second base is different.
"It's a little bit further," he said. "You just have to move your feet a little more and make sure you're not just sitting back. You have to get your feet set."
The left-handed-hitting infielder batted .305 in 2008 and was tabbed the Opening Day second baseman for '09. But he batted .236 in 135 games last year. The good news is that he never let his offensive struggles carry over onto the field.
Fontenot doesn't mind moving back and forth in the infield.
"It's always good to show the Cubs, or anybody else, that you can play multiple positions," he said. "You never know what's going to happen. I look forward to any opportunity I can get on the field, even if they want to throw me out in the outfield. I'm available for anything."
Last year, pitcher Sean Marshall was moved to left field for one batter so he could stay in the game in relief. If Marshall can handle the outfield, so can Fontenot. But the Cubs will worry about the infield for now.
"I was encouraged by what I saw," Piniella said. "He feels comfortable with it, which is more important than anything else."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.