BALTIMORE -- The illness that sidelined Mike Napoli on Thursday kept him out of Friday's game.
Manager John Farrell pulled Napoli in the third inning on Thursday after the first baseman experienced lightheadedness, dizziness and nausea. The problems have continued, and the Red Sox are searching for causes.
"[He] still has some symptoms of the illness," Farrell said before Friday's game. "He's unavailable today."
A virus has been circulating through the clubhouse over the past few weeks, and Farrell said that the team wondered if the cause could have been the very high humidity in Baltimore.
Napoli will undergo tests to try to solve the puzzle.
Red Sox trade Ciriaco to Padres
BALTIMORE -- The Red Sox sent infielder Pedro Ciriaco to the Padres on Friday in exchange for a player to be named or cash considerations.
Ciriaco had been designated for assignment on Monday.
Ciriaco batted .293 in 76 games last year for the Red Sox, playing several positions, but he had just a .216 average in 28 games this season. In addition, he had problems defensively, with seven errors in those 28 games.
Ciriaco is a true utility player, having spent time at every position except pitcher and catcher in his 135-game Major League career.
Boston calls up De La Rosa, sends down Wilson
BALTIMORE -- The Red Sox made two more moves on Friday to give their tired bullpen some help heading into the weekend.
Boston called up right-hander Rubby De La Rosa from Triple-A Pawtucket to take the spot of right-hander Alex Wilson, who threw 2 2/3 innings of relief in Thursday's 5-4 loss to the Orioles but was sent back down on Friday.
Boston strained its already overused bullpen in Thursday's game, as manager John Farrell needed to use five relievers in the 13-inning contest.
De La Rosa, obtained in last summer's big trade with the Dodgers, gives the Red Sox someone who can throw for a longer time if needed.
"[He] can give us multiple innings in the event that something unforeseen happens early in the game," Farrell said before Friday's game. "He's stretched out to 75, 80 [pitches]. He was the most fresh one on the roster that we could go and tap into to add to a bullpen that obviously has been taxed of late."
De La Rosa had a 0-1 record and 3.29 ERA at Pawtucket. He pitched 38 1/3 innings in 11 games, all starts, and held opponents to a .188 average in those games. But now he'll be pitching out of the bullpen.
De La Rosa appeared in 14 Major League games with the Dodgers -- 10 starts -- and has a 4-5 record. He has worked with Pedro Martinez to find more success at this level.
"I'm so excited," De La Rosa said. "I can't wait for tonight. I think I can do it."
Buchholz inches closer to possible Tuesday start
BALTIMORE -- Right-hander Clay Buchholz continued to improve on Friday, throwing to about 90 feet, and manager John Farrell said that if he shows the same improvement on Saturday, he'll be in line for a bullpen session on Sunday and could be able to start on Tuesday.
"He felt encouraged today over yesterday," Farrell said before Friday's game. "Everything's moving in the right direction."
Farrell said on Thursday that the Red Sox had moved Buchholz from his scheduled Sunday start in the finale of the Baltimore series to Tuesday in order to give him two additional days.
But he also emphasized that Tuesday's start isn't locked in, and they won't send Buchholz out there until everything feels right.
• The Red Sox remain the only American League team that has had a winning record all season. The Braves are the only other team in the Majors with a winning record in all of 2013.
• Jacoby Ellsbury stole a base in Thursday's loss and now is tied for the Major League lead, with 30. He's been on a roll lately, having stolen 17 bases in his last 14 games.
• Shane Victorino extended his hitting streak to eight games with a single in the first inning of Friday's game, and Jose Iglesias extended his to 15 with a single in the fourth.
Jeff Seidel is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.