WALTHAM, Mass. – Some big time names made their way into the Celtics practice facility on Thursday. So did some big time competition.

Boston opened its doors to six NBA Draft prospects, including three All-Americans in C.J. Fair, Aaron Gordon and Doug McDermott. All three of those players alluded to the fact that this workout was as competitive as they’ve seen during the pre-Draft process.

“I would say today’s been the toughest one,” said McDermott, who was chosen as the National Player of the Year by 14 different groups. “We all work out at our agencies with other guys, but once you step here where you’re going live a lot more, the competition is a lot tougher.”

Gordon followed that up by saying, “Really good players out here, man. Top to bottom, really good players… For the most part it was really fun and competitive and a lot of different skill sets out there on the floor.”

That seems to be exactly what the Celtics were aiming for in this workout. Four of the six players who participated in the workout were nearly identical in height and weight, yet all of them brought different skill sets to the table.

“It was kind of interesting,” McDermott said of that fact. “We’ve got some athletes, we’ve got some shooters, we’ve got some really good defenders. So once you throw them all together, it’s pretty cool to see.

“It’s a lot of competitive games and you just see a little bit of everything out there, which I think is what the Celtics really wanted to see.”

One of the more unique and competitive aspects of the workout was the fact that two former teammates were facing off against each other. Fair, who starred at Syracuse for four years, spent much of the day playing against Jerami Grant, who declared for the Draft after two years at Syracuse.

“It was kind of weird going against him,” Fair said with a smile. “We were guarding each other a lot during this workout. We’ve been playing against each other for two years.”

Today, however, they weren’t playing against each other as teammates. They were playing against each other as Draft prospects who are competing to be selected ahead of the other.

“Each workout is our opportunity,” said Fair. “You never know who you’re going to play for, so you want to come out in each city and show your best.”

Easier said than done when you’re working out with a group like this. Three All-Americans and a likely first-round selection made up two-thirds of Thursday’s workout group. No wonder why things heated up.