ST. PETERSBURG -- Ben Zobrist (lower back) and Carlos Pena (right foot) are both making progress, but they were both out of the lineup again on Monday against the Twins.

Zobrist felt good enough to go through some activity Monday afternoon at Tropicana Field.

"Played some catch, hit off the tee, and felt great, felt normal -- pretty much all of the normal moves I would make out on the field in a controlled environment," Zobrist said. "So tomorrow, get out on the field, take ground balls early, hit on the field early and make sure everything feels good. And if it feels good, then I'm hoping to be in there."

Zobrist did not feel like playing on the artificial surface at Tropicana Field contributed to his injury.

"I did it swinging," Zobrist said. "Swinging is the most violent activity I'm going to put on my lower back. Once I can take full hacks, [I'll be ready], and I took some really hard ones off the tee today. So hopefully, by [Tuesday], everything will feel completely normal and I'll be able to really let it fly."

If Tuesday doesn't work out, Zobrist believes Wednesday will be the date for his return to the lineup.

"For me, I'm thinking definitely Wednesday," Zobrist said. "Obviously, they want to be careful, so we'll see how it goes. But I'd like to be ready to pinch-hit soon, even in a couple of hours if they'll let me."

Maddon reported that Pena is progressing nicely as well, but did not have an estimated time for his return.

Rays place Sonnanstine on 15-day DL

ST. PETERSBURG -- Jeremy Hellickson was activated Monday from Triple-A Durham to start against the Twins. In a corresponding move, right-hander Andy Sonnanstine was placed on the 15-day disabled list with a left hamstring strain, retroactive to July 23.

Sonnanstine said the problem has bothered him since the Rays played the Yankees in New York on July 18.

"Other than that, just trying to get through it," Sonnanstine said.

The Rays used Hellickson for one start only before optioning him back to Durham after Monday's 4-2 win. Sonnanstine will be eligible to return on Saturday against the Blue Jays and he said he feels as though he'll be ready by then.

Sonnanstine said the problem has been nagging him "a little bit for a while now.

"But we got to a point where we needed to address the issue," Sonnanstine added. "[My] arm felt great, and I was available. But the nice thing about our starters is they've been going really deep. And with my role being the long guy, I haven't really been needed.

"[When you play a] 162-game season, you're going to have nicks and bumps all over the place. You try to minimize the damage as much as possible. This is probably the wise decision."

When Sonnanstine was asked if he thought he could have pitched through his problem if the Rays had not made the roster move, he answered: "That's a good question. I guess we'll never know."

Rays call up Johnson, option Hellickson

ST. PETERSBURG -- After Monday night's 4-2 win over the Twins, the Rays optioned Jeremy Hellickson back to Triple-A Durham and selected infielder Dan Johnson from the Durham roster.

"We brought [Johnson] up and he'll be up for tomorrow," Rays manager Joe Maddon said. "Here's a guy who is having one of the better Minor League seasons in recent history. We've always liked him. We're fortunate to have him. Having a guy like him permitted us to set a higher bar regarding potential acquisitions prior to the [Trade] Deadline."

Johnson was hitting .303 with 30 home runs and 95 RBIs in 98 games for the Bulls this season. With Carlos Pena nursing a sore right foot, Johnson is likely to see action at first base Tuesday night.

Rays fans best remember Johnson for his heroics on Sept. 9, 2008, the day he was selected from Durham to join the club in Boston. He arrived at Fenway Park at game time after flight delays. In his first at-bat for the Rays, he hit a game-tying pinch-hit home run off Red Sox closer Jonathan Papelbon, and the Rays went on to win, 5-4.

Johnson was named Durham's Player of the Year in 2008 and played in Japan during the '09 season.

Rotation gets a collective breather

ST. PETERSBURG -- Up until Monday night, the Rays had been the only team in baseball to use just five starters this season. Jeremy Hellickson's first Major League start interrupted that streak.

Asked to explain his rotation's resiliency, Maddon began his remarks with: "Knock on wood.

"First of all, I think they all have good deliveries, and I think the fact we monitor what they do and how they do things helps. I think our training staff is among the best there is. And furthermore, these guys are really motivated personally, and I think they take good care of themselves. There's a lot involved."

The Rays made the move to start Hellickson in order to push their rotation back a day, which gave each pitcher an extra day of rest during a tough stretch.

"Yeah, I mean it's nice, there's no doubt," said James Shields when asked about the move. "You can always use some extra rest. Obviously, all of us are competitive. We don't think we need the rest right now. We're all feeling pretty good right now.

"It's definitely nice to have the rest, and I think Hellickson is going to be able to get the job done tonight to give [Jeff] Niemann and the rest of the staff an extra day."

Matt Garza said he didn't disagree with the move.

"It's just something that threw a loop to us," Garza said. "We'll adjust. And I think they're looking out for the long haul, which is outstanding. These 20 games and then a day off, another 20 games and then one day off, so it will pay off in the end. So I think it's a good idea."