SAN FRANCISCO — Vladimir Guerrero Jr. homered twice to become the third-youngest player to hit his first two major league homers in the same game, and the Toronto Blue Jays beat the San Francisco Giants 7-3 Tuesday night.

Guerrero, who finished with three hits and four RBIs, became the youngest in franchise history to go deep as the Blue Jays won the opener of a six-game trip after losing five of six on a homestand in which they totalled eight runs.

Trent Thornton (1-4) pitched three-hit ball into the sixth inning for his first major league win. The rookie right-hander struck out seven and overcame five walks. Thornton also singled twice to help the Blue Jays break out of their offensive funk.

The touted 20-year-old Guerrero homered in the first inning against Giants opener Nick Vincent (0-2), his first in 14 big league games. His drive to straightaway centre was measured at 111.3 mph and travelled an estimated 438 feet.

The Toronto slugger had a hard-hit single in the second then added an even more impressive blast in the sixth off Reyes Moronta, a three-run drive estimated at 451 feet.

The only players younger than Guerrero to hit their first two home runs in the same game are Brian McCall in 1962 (19 years, 248 days) and Manny Machado in 2012 (20 years, 35 days).

Two-sport star Danny Ainge was the youngest Blue Jays player to homer, doing so on June 2, 1979 at 20 years, 77 days old. Guerrero is younger by 18 days.

Guerrero grounded out in his final at-bat. The son of Hall of Famer Vladimir Guerrero entered the day batting .191 with one RBI.

The family already had long-ball history at Oracle Park — the elder Guerrero won the 2007 Home Run Derby at the waterfront stadium.

Toronto got an overturned replay and added two runs in the first following Guerrero's first home run.

Freddy Galvis hit an RBI double that fell just over the glove of charging right fielder Steven Duggar but was ruled foul by first base umpire Adrian Johnson. Blue Jays manager Charlie Montoyo asked for a replay. After a brief review the call was overturned. Bill McKinney then doubled in Galvis.

Pablo Sandoval homered for San Francisco.

The Giants used an opener for the first time. Vincent allowed three runs and four hits in one inning in his second career start.

TRAINERS ROOM

Giants: C Buster Posey caught Drew Pomeranz's bullpen session and could be activated off the concussion list as early as Friday. Posey's next step will be running the bases Wednesday. ... Pomeranz threw 60 pitches in his bullpen.

UP NEXT

Edwin Jackson will make history when he pitches for his 14th major league team in his Toronto debut Wednesday. A 35-year-old right-hander, Jackson was acquired by the Blue Jays from Oakland on Saturday for $30,000. He made three minor league starts for the Athletics, two at Triple-A and one at Class A. RHP Shaun Anderson makes his major league debut for San Francisco.

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