Arm problem lands Chris Sale on DL

The Chicago White Sox confirmed late Monday that staff ace Chris Sale is headed to the 15-day disabled list with a strained flexor muscle in his throwing arm.

Left-hander Charlie Leesman will be called up from Triple-A Charlotte to start Tuesday's game at Detroit to face Justin Verlander, while right-hander Andre Rienzo will start Wednesday in the spot vacated when Felipe Paulino went on the DL with rotator cuff inflammation.

Forearm discomfort is often the first indicator of damage to the ulnar collateral ligament, and subsequent Tommy John surgery in a worst-case scenario, but Sale underwent an MRI that showed no ligament damage, and the White Sox are optimistic for a quick return. General manager Rick Hahn says the White Sox are erring on the side of caution.

The news comes four days after the 25-year-old Sale threw 127 pitches in an eventual extra-inning defeat to the Boston Red Sox. A source indicated to ESPNChicago.com's Doug Padilla that the left-hander was dealing with "tenderness" even before that start last week, but it's not uncommon for Sale to pitch through soreness.

White Sox manager Robin Ventura said earlier Monday from Detroit that Sale was not expected to make his regular turn in the rotation Tuesday because of general soreness -- and there was no timetable on when he might pitch again.

If discomfort was present before he faced the Red Sox, that would make his seven-inning, one-run, one-hit outing even more impressive. And it would also help to explain why Sale wasn't as efficient as usual by walking three and going deep into counts. But he did strike out 10 against an opponent with a patient approach at the plate.

It would also make the lengthy outing a dangerous one. Yet there is no indication that anybody, including Sale, felt that his discomfort leading into his last start was anything out of the ordinary.

"He's always sore after he pitches, not in an alarming way," Ventura told reporters in Detroit before Monday's game. "For right now that's where we're at. He's sore so I would imagine he's not pitching [Tuesday]."

Sale opened the season 3-0 with a 2.30 ERA over his first four starts and was the rare dependable pitcher on a staff that had experienced some major struggles. The team's combined 5.18 ERA was 29th of all 30 major league teams heading into play Monday.

In three seasons as a starter, Sale is showing a track record for early-season arm discomfort.

In 2012, the White Sox decided to send him back to the bullpen after early May elbow tenderness. He made one relief appearance then returned to the rotation after a clean MRI showed there was no serious issue. Last season, Sale went 16 days between starts, from late May to early June, after experiencing shoulder tendinitis.

In both cases, Sale went on to have a solid season, finishing sixth in Cy Young Award voting in 2012, and fifth last year.

In the postgame locker room after Sale's lengthy start on Thursday, catcher Tyler Flowers seemed to give indications that all was not normal.

"You know, he looked fine," Flowers said, making the word "fine" sound more like a question than an emphatic statement. "I think he was trying to dig down a little bit. I was trying to calm him down. Mixing in a couple more changeups seems to always bring him back a little bit more under control."

Sale was asked about his body language late in the game, when he seemed to be taking more time between pitches. That tactic isn't unusual for a pitcher that late in an outing to give his arm more time to recover before throwing the next pitch.

"I think it was more just trying to focus," Sale said. "I think it's no secret that my emotions were running a little high. Just trying to dial it back a little bit and try to make my pitch. Getting that late in the game, that high pitch count, adrenaline kicks in and gets you through that. It wasn't anything of getting tired or anything like that. It was just trying to compose myself and protect the pitches that I had."

Sale went 11-14 with a 3.07 ERA in 30 starts last season, emerging as one of the American League's top pitchers amid a dismal season for the White Sox.