Boesch hit a go-ahead RBI single in the 10th inning to give the Tigers a 4-3 win over the Kansas City Royals on Friday night.
"I just didn't want to do too much," Boesch said. "I just wanted to make sure I was under control and just try to play pepper back up the middle. I wanted to do that."
The Tigers extended their lead in the AL Central to four games over the Cleveland Indians, who lost in extra innings around the same time the Tigers were winning.
Porcello, who had won his previous five starts, took a 3-0 lead into the seventh.
"Every time he goes out there now, we really feel we're going to win," Boesch said. "He's really been pitching well. He's been growing all season long, getting better as the year goes on. That's what we need from him. He's stepping up big.
Manager Jim Leyland pulled Porcello after he gave up a run on three singles with one out in the seventh.
"I feel bad for Rick," Leyland said. "He deserved to get a win. He was fantastic. I'm sorry he didn't get a win."
Royals starter Felipe Paulino gave up three runs and six hits in 6 2/3 innings, striking out seven and walking two.
Porcello had a string of wins in five straight starts snapped. He left with one out in the seventh after giving up Giavotella's RBI single.
"The team got the win and that's the biggest thing," Porcello said. "Obviously, it's nice for yourself personally to get a win, but we got the win and started the series off to a good start. That's the bottom line, the most important thing. I definitely had plenty left in tank. The skipper wanted to go with a lefty-lefty matchup. That's his call."
Giavotella went 2-for-3 in his big league debut, with a double, a walk a steal and a run in addition to his RBI single.
"I had some jitters coming into the game, some butterflies here and there, but after that first ground ball I calmed down and felt comfortable out there," Giavotella said. "On the double, I looked up into the stands and saw my dad. He gave a little fist pump and I gave one back to him. It was a nice moment."
The Tigers began a stretch Friday where they are playing 12 of 15 games against AL Central opponents. ... Tigers first baseman Miguel Cabrera singled in the fourth for his 80th hit in 65 games against the Royals. ... Royals DH Billy Butler extended his hitting streak to 11 games with a seventh inning leadoff single. ... The Royals optioned infielder Yamaico Navarro, who they acquired in a trade, to Omaha to make roster space for Giavotella. ... The Royals fell to 10-7 in extra-inning games. ... Right-hander Justin Verlander, who starts Saturday, is seven strikeouts shy of tying Denny McClain (1,150) for ninth place on the Tigers career list. Verlander will be seeking his 99th career win. ... Left-hander Danny Duffy, scheduled to start for the Royals on Saturday, has struck out 40 in 37 1/3 innings in his past six starts. In his first six, Duffy struck out just 20 in 30 1/3 innings in his first six starts.