PITTSBURGH -- The Giants saw Fernando Tatis Jr.'s debut with the Padres on Opening Day and were defeated in five innings in Saturday’s rain-shortened game after Cole Tucker crushed a tiebreaking home run in his debut with the Pirates.

Their run against top prospects could continue this week when they head to Toronto, as there has been speculation that Vladimir Guerrero Jr. could receive his first callup with the Blue Jays during the Giants’ upcoming two-game series at Rogers Centre.

“That’s what I’m hearing, that he’s going to make his debut against us,” manager Bruce Bochy said Sunday.

That said, while it was said Guerrero might make his Major League debut as soon as Tuesday, according to an MLB.com source, that's not going to happen and instead Guerrero's debut won't be happening until at least later in the week. 

The Blue Jays have not yet made a formal announcement on Guerrero, who missed most of Spring Training with a left oblique injury but is now healthy. The 20-year-old third baseman, who is ranked the No. 1 prospect in baseball by MLB Pipeline, has appeared in five games for Triple-A Buffalo this season, batting .412 (7-for-17) with two home runs and six RBIs.

Left-hander Travis Bergen, who was selected from the Blue Jays in December’s Rule 5 Draft, played with Guerrero for about a month at Double-A New Hampshire last year and said the hype is warranted.

“He’s a special player,” Bergen said. “I feel like I’ve played with a lot of good players in the Minor Leagues, and he’s far and away the best Minor League hitter. If you asked me last year who’s the best hitter you’ve ever seen, the answer would be him.”

For Bochy, who played with Tatis’ grandfather, Fernando, as a Minor Leaguer in the Astros’ system and managed against Vladimir Guerrero Sr., the arrival of their younger namesakes has served as a reminder of the longevity he’s enjoyed in the game.

“It shows you that you’re getting old,” Bochy said. “That’s the biggest thing about this. It’s kind of cool to see these kids of ex-teammates and guys I managed against come up and do so well. You can see the talent that these young kids have.”

Charity auction

Major League Baseball umpires will offer up more than 400 items, including autographed sports memorabilia, one-of-a-kind VIP experiences and upgraded ticket packages during the 11th Annual UMPS CARE Charities online auction. The auction is currently underway and closes at 10 p.m. ET on April 29.

All proceeds from the online auction support UMPS CARE Charities youth programs, which connect children and families in the communities in which the umpires work all season through the game they love.