Infante was not in the starting lineup for the first time in 18 games.
The veteran second baseman, who has been having an All-Star caliber season, went hitless in eight at-bats on Saturday and Sunday against Tampa Bay. Since May 23, he is hitting at a .239 clip, which has lowered his season average to .296.
Donovan Solano was given the start at second base in the series opener with the Red Sox.
"I think he's mentally tired," Guillen said. "He's been playing every day. Hopefully, in a couple of days, we'll get him back on track."
Chances are Infante will be back in the lineup on Tuesday. The day off, Infante says, gives him a chance to clear his mind.
Physically, Infante is fine. He had dealt with a tight right hamstring early in the season.
From May 19-22, he was away from the club for three days due to the death of his grandfather.
Infante was batting .326 on May 22. He's had two multihit games since then, with the most recent coming when he was 3-for-5 against the Rays on Friday.
"You don't hit, you're not in the lineup," Infante said.
Solano, meanwhile, will make his first big league start at second base. A natural shortstop, he now is assuming the utility infield position since Donnie Murphy was designated for assignment after Saturday's game.
Solano has started three games in left field, and he entered Monday having played one inning at second base at the big league level.
At the plate, Solano is off to a nice start, going 9-for-19 with two doubles entering Monday.
Infante admits his swing and timing are off. He's not recognizing pitches and he's reaching at pitches.
"I'm pulling the ball a lot," he said. "I don't feel good. My top hand, too. Keep working, practice every day and we'll see. Maybe I'll go 4-for-4 tomorrow."