The 23-year-old Bastardo, who speaks little English and was not made available to reporters, was summoned from the IronPigs on Saturday to take the roster spot previously occupied by Brett Myers.
Myers was placed on the 15-day disabled list Friday and is scheduled to undergo surgery on his right hip this week. The procedure is expected to sideline Myers for 10 to 12 weeks and possibly the entire season.
"Antonio is very talented," said Phils reliever Sergio Escalona, who was teammates with Bastardo in Triple-A. "He has a good fastball and can change things up. I'm sure he is very happy to be here with the Phillies."
Bastardo, 23, was 3-2 with a 1.89 ERA in 11 games (seven starts) with Lehigh Valley and Double-A Reading. In two starts after being promoted to the IronPigs, Bastardo struck out 12 while walking just three and allowing 11 hits in 13 innings.
"We've had some real good reports on him," Phillies manager Charlie Manuel said Friday, before the decision was announced. "He's had some real good outings since he's been in Triple-A."
The Phillies will officially make the roster move before Tuesday's game in San Diego.
If making your debut isn't tough enough, Bastardo will be opposed by Jake Peavy, the 2007 National League Cy Young Award winner.
"I'll try to calm him down and make him feel comfortable," Carlos Ruiz said. "I don't want to put too much pressure on him and have him try to do too much."
The Phillies catcher is looking forward to catching the rookie lefty.
"I heard he has a great power fastball and he throws hard," Ruiz said.
The same goes for reliever J.C. Romero, who is eligible to be activated Wednesday after serving his 50-game suspension for violating Major League Baseball's policy against performance-enhancing drugs.
"He's a very aggressive guy, left-handed, kind of has a lot of life in his fastball," Romero said. "And last time I saw, he got a nice breaking pitch. You never know what's going to happen when he faces big league hitters, but we feel confident. That's the reason why we called him up. And I think the front office and all those people felt confident about him having the talent to execute at this level and we're going to certainly prepare him on the mental standpoint to help him relax, so when the time comes, he can give us a chance to win."
Andy Jasner is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.