TORONTO — Red Sox manager John Farrell wasn't with the Red Sox at Rogers Centre on Saturday. His plan instead was to be pacing around in the right-field corner at Kauffman Stadium in Kansas City, where his son Luke was to make his major-league debut for the Royals.

Farrell was summoned from Triple-A Omaha to pitch the first game of a doubleheader for Kansas City against the Minnesota Twins. Royals manager Ned Yost said that he'd sent John Farrell a text message to let him in on the news even before he told Luke Farrell, who spent two seasons with the New Bedford Bay Sox. Red Sox president Dave Dombrowski gave John Farrell permission — encouragement, even — to leave the team for the day and be there in person for his son's debut.

"John, he asked my opinion about it four or five days ago when he found out," Red Sox bench coach Gary DiSarcina said. "I was like, 'I know where my parents were on Sept. 23, 1989, sitting in the stands when I made my big-league debut. I'm sure you know where yours were.' ... He was torn a couple of days ago. He wants to stay. He feels his duty is here. But it's going to be a proud moment for him."

A sixth-round pick of the Kansas City Royals out of Northwestern in 2013, Luke Farrell compiled a 3.83 ERA in 82 1/3 innings pitched at Triple-A before his call-up. He pitched last winter for Licey in the Dominican Republic's winter league, the first time his father had gotten a chance to see him pitch since he was in college.

And even before his father confronted and beat cancer two years ago, Luke Farrell twice had to have surgeons remove a tumor in his neck. That figures to make Saturday's father-son reunion that much more special.

"If there's a word I could sum him up with, it's 'determination,'" John Farrell said late Friday night. "It's a great day for him."

Luke Farrell lasted just 2 2/3 innings in his big-league debut, an outing marred by a pair of bases-loaded walks. He struck out three and walked two while yielding five runs on seven hits.

Marrero takes on sliders

The slider that Deven Marrero hit for a two-run single in Friday night's 11th inning wasn't a particularly good slider. It spun and stayed up and gave him every opportunity to line it into right field for a two-run single.

But Marrero doesn't have to hit good big-league sliders to be a viable big-league hitter. He has to lay off the good big-league sliders and hit the sliders that don't get to their intended target — as he did Friday.

"You can't really put it in play when it's in the freaking other batter's box," he said. "Those are the tough ones."

For Marrero, Friday's base hit was just his second hit of the season on a slider. He added a third hit on Saturday, an infield single squibbed toward third base. He's still just 3-for-26 with 13 strikeouts on sliders in the big leagues this season. For the season, he's hitting .195 with a .240 on-base percentage and a .327 slugging percentage with 39 strikeouts in 123 plate appearances.

But Friday night's 11th-inning triumph was a reminder that hope for improvement remains.

To address his deficiency, Marrero has made a part of his daily routine two 40-pitch sessions against a pitching machine that feeds him nothing but sliders. The mission has been to recognize the break on the pitch so that he can tell if it will stay on the plate or if it will end up in the other batter's box.

But even the machine can't give Marrero much of a sense of what sliders look like coming out of the hands of pitchers — especially pitchers with whom he's still getting familiar. That aspect has required video study as well as frequent conversations with longtime friend Mookie Betts ahead of at-bats, trying to get a sense for what to expect from the delivery he'll face — and how to pick out the sliders he can hit.

"It's about recognition," he said. "Some pitchers seem quicker than others. Some guys have different arm slots or throw in different spots. Especially when you haven't faced a pitcher, you have to find out where it needs to start if it's going to be a strike."

E-Rod works his way back

Eduardo Rodriguez will make a rehab start at Triple-A Pawtucket on Tuesday, his second rehab start. That suggests veteran newcomer Doug Fister will take yet another turn in the Red Sox rotation after a pair of starts that have yielded solid if unspectacular results.

Rodriguez threw 69 pitches in three innings at Double-A Portland on Thursday as part of his progression back from a knee subluxation he suffered a month ago. Rodriguez had a 2.77 ERA in his first 55 1/3 innings pitched for the Red Sox this season before he slipped and fell in the bullpen at Camden Yards on June 1.