Jorge De La Rosa has been the Rockies' most consistent and durable starter this season, stretching a team-best 3.38 ERA into a 7-3 record midway through June.
Colorado believes the left-hander will make his 14th start of the year on Wednesday against the Nationals, but there is reason to be concerned.
De La Rosa pitched through a small cut on his left middle finger in his last outing, a 10-9 Rockies victory over the Padres on Friday. Just in case De La Rosa can't pitch Wednesday, the Rockies have summoned right-hander Chris Volstad to Denver from Triple-A Colorado Springs, but haven't activated him.
Still, even with the insurance, De La Rosa is planning to take the mound in the second game of the Rockies' three-game series with Washington.
"It's fine -- I didn't have to put anything on it," De La Rosa said. "It's healing."
Since May 7, De La Rosa has won five consecutive decisions.
Opposing the southpaw for the Nationals will be Ross Ohlendorf, who will be called up to make the start while Nate Karns gets sent down.
Wednesday will mark Ohlendorf's first big league appearance since August 17 of last season when he was with the Padres. He pitched 48 2/3 innings in San Diego in 2012, making nine starts and finishing the year with a 7.77 ERA.
Rockies: Escalona to the DL, Outman called up
After leaving Sunday's game in pain, right-hander Edgmer Escalona was placed on the 15-day disabled list Tuesday when an MRI Monday revealed inflammation in his right elbow. Escalona (1-2, 4.18 ERA) was bothered by elbow soreness for a week or more before Sunday.
In his place, the Rockies called up righty Josh Outman (2-0, 4.94 ERA), who was just demoted to Triple-A Colorado Springs on Saturday.
"There's a lot more fluidity in this game than most jobs," Outman said, smiling. "Sometimes things take forever to play out and sometimes it happens in 48 hours or less. I went to the Springs, threw a bullpen session, watched the game on Sunday and found out I was coming right back. Sometimes it works out."
Nationals: Strasburg throws sim game
Nationals ace Stephen Strasburg threw three or four innings in a simulated game at Coors Field Tuesday and came away feeling strong, a positive sign as he recovers from a strained muscle in his back.
Strasburg is eligible to come off the 15-day disabled list Sunday, and said he feels like he will be ready to make his 13th start Sunday against the Indians in Cleveland. He will toss the ball around Wednesday and plans to throw a bullpen session Friday.
"They wanted me to throw only like 56 pitches, but I didn't even really feel like I threw at all," Strasburg said. "I feel the strength has really stayed there, even though I missed a couple starts."
Strasburg lasted only two innings in his last start against the Braves May 31. Washington pushed back his next start two days, but when he could not toss a bullpen session ahead of that start, the Nationals put him on the DL.
• The Nationals' streak of totaling double digit hits in four straight games came to an end Tuesday when they collected eight hits.
• The Rockies are 5-2 against National League East teams this season.
Tyler Emerick is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.