Toronto Blue Jays pitching coach Pete Walker and bullpen coach Dane Johnson looked on intently from behind the mound.
Brook Jacoby, the Blue Jays hitting coach, was watching from behind the batting cage while third-base coach Luis Rivera watched from near the on-deck circle.
It was one of the most scrutinized simulated throwing sessions in recent memory for the Toronto Blue Jays, which was understandable, given the subject in question was Roberto Osuna.
The prized Toronto closer, on the disabled list since the beginning of the Major League Baseball season with a sore neck, threw from the mound here at Tropicana Field Saturday afternoon.
The Blue Jays are to play the Tampa Bay Rays here Saturday night in the third game of their four-game set.
It all went very smoothly – 24 pitches, to be precise – and afterward, both the player and the pitching coach said Osuna felt ready to go.
That can't happen until Tuesday, when Osuna is eligible to come off the DL, just in time to return to the lineup for Toronto's regular-season home opener against the Milwaukee Brewers.
"I think I'll be ready by Tuesday," Osuna said after the throwing session. "Might throw a little around tomorrow or Monday, just to make sure I'll be 100 per cent on Tuesday. But, yeah, definitely no issues, no more pain in my neck or back, feeling great."
That's good news for the Blue Jays, who can ill afford to be without their solid right-hander at the back end of the bullpen for an extended period of time.
The 22-year-old has tallied 56 saves in the two years he has held the job for Toronto since breaking into the big leagues.
'He felt good, each and every one of [the pitches]," Walker said. "Threw a warmup before he went in, free and easy. Neck feels great, so it was very encouraging."
Walker said he kept a practised eye primarily on the action of Osuna's throws and the freedom of his delivery.
"His action looked like the same old Osuna and that's really what I was concerned with and looking for," Walker said. "And he certainly looked good today."
After Friday night's marathon, a 10-8 Tampa Bay victory in which starter Francisco Liriano could not get out of the first inning for Toronto, manager John Gibbons was forced to use five members of his bullpen to get through the game.
As a result, the Blue Jays made a roster move on Saturday to try to freshen up that group, selecting the contract of right-hander Casey Lawrence from Toronto's Triple-A affiliate in Buffalo.
To make room on the 25-man roster, reliever Dominic Leone was sent down to Buffalo.