PITTSBURGH -- The Pittsburgh Pirates placed rookie reliever Josh Sharpless on the 15-day disabled list Friday due to a sprained right ankle.

Sharpless, who has allowed one earned run in 2 2/3 innings since being promoted from Triple-A Indianapolis on Aug. 1, suffered a high ankle sprain when trying to field a ball Wednesday night in Houston.

"It was an unathletic guy trying to make an athletic play," said Sharpless. "It didn't work."

Sharpless has had a history of ankle problems throughout his athletic career. He's broken each ankle once and has had countless other sprains.

"It's a little stiff and a little sore, but it's nothing I haven't felt before," said Sharpless. "I have pretty weak ankles."

Although the injury is not considered to be serious, the Pirates were concerned that Sharpless might overcompensate for the ankle problem and do damage to his arm or shoulder if he continued to pitch.

"This is a young arm that is obviously very intriguing to us," said Tracy. "I think it's very prudent on our part to err on the side of caution."

Tracy said that Sharpless will likely begin throwing bullpen sessions well in advance of his activation from the disabled list later this month.

Chacon skips start: Newly acquired starter Shawn Chacon will be forced to skip his scheduled start on Monday due to what he described as a "probable tear" in the cartilage of his right knee.

Because doctors have informed Chacon that he will not do any further damage to the knee by continuing to pitch, the right-hander has opted to wait until after the season to undergo corrective surgery.

"I could have the surgery done now, and it would basically end my season," said Chacon. "With them telling me that I won't hurt it any worse, it's just a matter of trying to keep it as strong as I can and dealing with whatever pain I have to deal with.

"If I'm not going to make it any worse, I might as well go ahead and pitch."

Chacon has twice had arthroscopic surgeries performed on the knee in the past, and the knee is often troublesome. It was only when the swelling and pain reached unmanageable levels after his start Wednesday that Chacon opted to have the knee reexamined.

"It's just something that I've had to deal with," said Chacon. "It was pretty noticeable this past week. There was a bunch of fluid in there, and I knew something wasn't right."

Chacon had fluid drained from the knee on Friday and received a cortisone shot. He hopes to be back on the mound next weekend in Cincinnati against the Reds.

Reames promoted: The Pirates purchased the contract of right-hander Britt Reames from Indianapolis on Friday to replace Sharpless on the active roster.

Reames went 4-2 with a 2.84 ERA in 13 appearances (11 starts) with Indianapolis. He previously pitched in 95 big-league games with the A's, Expos and Cardinals, including two relief appearances with Oakland in 2005.

Reames, who will celebrate his 33rd birthday on Aug. 19, admits that he was beginning to wonder if he'd get another shot at the big leagues.

"You think about it," said Reames. "You want to get a chance to pitch in the big leagues. But you can only control what you can control."

Either Reames or Victor Santos will start Monday for the Pirates against the Brewers in Chacon's absence. The other will be used in long-relief duty, possibly as early as this weekend against the Cardinals.

"One of them would be the likely choice," said Tracy. "How things go this weekend will go a long way towards determining that."

Late night: Because their chartered flight from Houston did not arrive until 4:05 a.m. ET on Friday morning, Pirates players were not required to report to PNC Park until about two hours before game time Friday night.

"We got to the airport [in Houston] and the plane wasn't even there because of delays," said Nate McLouth, one of only a handful of Pirates players who were at PNC Park when the clubhouse was opened to the media at 3:30 p.m. ET. "When it got there, a bunch of people had to get off and they had to clean it. We didn't get in until after 4 [a.m.]. It was tough, but I got to sleep in until 2 [p.m.]."

Like commercial airline passengers, the Pirates weren't able to take any liquids on board with them as a result of the foiled terrorist plot that was revealed Thursday morning.

So why was McLouth one of the few players who chose to arrive at the park early?

"I'm hungry," McLouth said, smiling. "I haven't had a chance to shop in a while."

On deck: The Pirates and Cardinals will continue their three-game series Saturday night at PNC Park at 7:05 ET. Ian Snell (9-8, 4.78) will start for the Bucs against Cardinals right-hander Jeff Weaver (2-2, 6.93).