MOOSIC, Pa. — Bobby Meacham stood against the dugout railing before Thursday night's game explaining how the newest addition to his Buffalo Bisons lineup had found so much success at such a young age.

Then, Vladimir Guerrero Jr. took the field in an International League game for the first time this season and put on an efficient demonstration of his manager's words.

The barely 20-year-old third baseman slammed the first ball he put in play hard off the wall the other way for an RBI double and pulled the next well over the fence for a three-run homer when the Bisons fell to the Scranton/Wilkes-Barre Red Barons, 9-8, in a 10-inning game.

The Toronto Blue Jays prospect, serving as designated hitter for the night, showed why he is regarded as one of baseball's hottest up-and-coming players. He finished 2-for-4 with a walk, two runs and four RBIs in his first game above Class A after having his spring disrupted by an oblique muscle injury.

"I felt very happy," Guerrero said through interpreter Tanya Bialostozky, a mental performance coach with the Blue Jays. "I was ready to work. I wanted to help out the team.

"We wanted to win and I wanted to put my best effort out on the field today."

Meacham's pre-game description centred around how well Guerrero managed at-bats and pitch counts. The Buffalo manager painted the picture of a player performing well beyond his years and of one that, as he said, succeeds in doing what everyone else is trying to do.

"The one main thing, I think, watching him hit is that he's not swinging at pitchers' pitches, specifically early in the count," the manager said. "He's waiting for them to make a mistake early and when they do, he's ready to jump on it.

"That puts him in good hitting counts and then when they do get ahead of him, he's tough enough to cover. Most players can't cover the whole plate, but he can."

Guerrero covered the plate well enough in his first at-bat to foul off three pitches, including one with a full count, to draw a walk.

With the Bisons trailing 5-0 in the third, Guerrero worked a 3-1 count, then lined a double off the wall in right-centre to drive in the first run.

Guerrero topped that effort in the fifth. Kept alive when RailRiders first baseman Mike Ford did not get to a foul popup in front of the dugout, Guerrero launched a shot down the left-field line and over the fence, the bullpen and the pedestrian bridge behind the bullpen at PNC Field.

Before he was done, Guerrero reached on an error and scored in the seventh, then grounded out in the ninth.

Toronto moved Guerrero from Class A Dunedin to triple-A Buffalo in time to start a four-game series Thursday night. Meacham said Guerrero practised and played enough in Florida that the manager is not evaluating health, just performance.

"We want to make sure what he started to do last year continues on to this year," Meacham said.

Guerrero hit .381 with a .437 on-base percentage and .636 slugging percentage a year ago across four minor-league clubs. He had a 20-homer season as a teenager.

That successful run culminated in a .336 average with six home runs and 16 RBIs in 30 games with Buffalo last season.

Following the injury, Guerrero started this season 4-for-15 (.267) with Dunedin in the Florida State League where he had a double, two runs and an RBI. Thursday's game looked more like a continuation of 2018.

Guerrero played four times in six days in Dunedin and had Wednesday off to travel. Following rehab plans from the organization's medical staff, Meacham said Guerrero will play again Friday as the starting third baseman.

During Thursday's batting practice, Guerrero took groundballs at third base.

"The staff did a really good job of taking things easy and slowly and making sure I was ready," Guerrero said. "They did a great job of preparing me for this."

The son of 2004 American League Most Valuable Player Vladimir Guerrero was signed by the Blue Jays as a 16-year-old.

Ben Cherington, Toronto's vice president of baseball operations, is also in town for the series, but Meacham said that Cherington's presence is routine for a series at Scranton/Wilkes-Barre. Other instructional staff are also with the team on a rotating basis, but no additional staff are in place to evaluate Guerrero while the Blue Jays decide when to schedule his highly anticipated Major League debut.