BOSTON -- Major League Baseball suspended Red Sox Minor League left-hander Miguel Pena for 100 games after he tested positive a third time for a drug of abuse. The suspension is effective immediately.

MLB's joint drug prevention and treatment program distinguishes between performance-enhancing drugs and drugs of abuse, which include marijuana, cocaine, LSD and opiates.

In 13 starts with the Double-A Portland Sea Dogs, the left-hander went 2-2 with a 6.41 ERA. Pena was drafted in the sixth round of the 2011 First-Year Player Draft.

This is Pena's second suspension in two years. He was suspended for 50 games in April 2013.

Buchholz to make second rehab start Thursday

John Farrell wants Clay Buchholz to reach the 90-pitch mark. (AP)

BOSTON -- Red Sox right-hander Clay Buchholz will make his second rehab start with Triple-A Pawtucket on Thursday, with his pitch count set to increase.

"We need to get him up to 90 pitches or so in this next outing," said Red Sox manager John Farrell.

In his first rehab start with the PawSox, Buchholz went 4 2/3 innings, allowing three runs, including a pair of solo shots, on four hits. He tossed 62 pitches, 42 for strikes.

"Clay went out and accomplished some of the delivery adjustments he's been working on. Overall strikes were improved," Farrell said. "Higher percentage of strikes and better power overall. He also had more defined shape to his pitches."

The right-hander has been on the disabled list since May 28 with a hyperextended left knee.

In 10 starts for Boston this season, he's 2-4 with a 7.02 ERA.

Sox hope Victorino returns during West Coast trip

TOR@BOS: Victorino lifts a solo home run to left

BOSTON --- The Red Sox are hopeful Shane Victorino will rejoin the club on its West Coast road trip following his rehab assignment with Triple-A Pawtucket this week.

Boston begins a four-game set against the Athletics on Thursday, followed by a three-game series in Seattle. Victorino was scheduled to start for Pawtucket on Monday and Tuesday, when the Sox are home against the Twins.

"We've got a tentative plan in place that has him returning to us while we're on the West Coast, but that doesn't pinpoint an exact day, either," Farrell said. "Whether its Oakland or Seattle, that's to be determined."

Victorino reinjured his left hamstring May 23 and has been on the disabled list since. That same ailment caused him to miss the first 22 games of the season.

Saturday, he went 0-for-2 and played five innings in the field during his first rehab start. Monday and Tuesday, he'll play more, Farrell said.

The Red Sox haven't gotten a lot production from their outfield, and while Victorino's .242/.276/.352 slash line in 21 games hasn't done much to help, the group needs a shot in the arm.

Boston's outfield ranked second to last in the Majors in both average and OPS, and fifth from the bottom in WAR at just 0.1 entering Monday. Still, Farrell doesn't want to rush Victorino back.

"We're going to continue to have some kind of schedule once he returns to us rather than turn him loose for nine innings every day," Farrell said. "He's had this recurring injury twice, so we've got to be mindful."

The club has optioned Daniel Nava to Pawtucket twice this season, but since his return earlier this month, has a .379/.486/.448 slash line in 29 at-bats. Grady Sizemore, hitting .216/.288/.324 in 52 games, has seen reduced time with Brock Holt getting a shot in the outfield because of his hot bat. So with Victorino's return nearing, there will be an odd man out, which could be utility man Jonathan Herrera.

"Provided there are no setbacks, there's going to be a need for a roster decision on his return," Farrell said.

Worth noting

• Felix Doubront didn't allow a hit and struck out 10 in a rehab start Sunday for Triple-A Pawtucket, but Farrell said the next step in the lefty's rehab process hasn't been determined. Doubront has been on the disabled list with a left shoulder strain for more than three weeks.

Will Middlebrooks went 1-for-3 in the first game of a rehab assignment Saturday and was back in the lineup for Pawtucket on Monday. He was the team's designated hitter in that game, but played third base Monday while he recovers from a broken right index finger that has given him more trouble in the field than with a bat.

The Red Sox held Xander Bogaerts out of the lineup with flu-like symptoms Sunday, but he pinch-ran in the ninth and was back Monday, starting at third base and batting second.