A victory in Milwaukee would eliminate the Bucks and send the Celtics into the second round against the Philadelphia 76ers.

Jim Fenton The Enterprise @JFenton_ent

BOSTON – There is one thing that is certain about the Celtics’ weekend playoff plans.

One way or another, they are going to be spending Saturday night at the TD Garden, tipping off against an opponent at 8 p.m.

Still to be determined is whether the Celtics will be playing a dramatic Game 7 against the Milwaukee Bucks to close out the opening round or starting a second-round series with the surging Philadelphia 76ers.

The answer to that question will be delivered on Thursday night when the Celtics attempt to finish off the Bucks in Game 6 at the Bradley Center (8:05, TV: TNT and NBC Sports Boston; radio: WBZ-FM/98.5).

If the Celtics can pull that off, then they would have just one day to prepare for the 76ers, who are sitting back after wrapping up their first series win since 2012 on Tuesday night.

The Celts departed for Milwaukee Wednesday afternoon full of confidence and momentum following a 92-87 victory the night before, but the Celtics were in a similar frame of mind last week.

After opening the series with two home wins, they went to Wisconsin and were routed in Game 3, then fell short in a comeback bid after trailing by 20 points in Game 4.

This time, a ticket to the second round will be the prize if the Celtics can pick up a road playoff win, one that would finish off the Bradley Center with the Bucks moving into a new building in the fall.

“We have the same mentality (as before),’’ said Marcus Smart, who returned from a six-week absence in Game 5. “The only difference is we’ve got an extra part of our team back with me here.

“We have a little momentum and confidence. We have to go in and play the game like it’s our last one.’’

The series seems destined to go the distance, with the Bucks outscoring the Celtics by just one point, 520-519, through five games. Each team faced large deficits on the road (the Celtics by 20, the Bucks by 16) and nearly rallied to win.

And adjustments have worked for both sides with the Bucks turning to Thon Maker, Jabari Parker and Matthew Dellavedova in Games 3 and 4 and they produced, and Celtics coach Brad Stevens starting Semi Ojeleye in Game 5 while moving Al Horford to center.

It is likely that Stevens will stick with the smaller lineup that was more effective against Giannis Antetokounmpo, who took only 10 shots and scored 19 points in the Game 5 loss.

“I just think that it gives our team a different look,’’ said Horford. “One of the strengths of our group is that we have multiple guys that can play multiple positions.

“The Bucks had us against the wall. They beat us twice. We needed to make an adjustment. We needed to do something. Coach saw that and he went with his gut.’’

Ojeleye, making his first NBA start, went 32 minutes and was matched up against the Greek Freak on numerous occasions.

The Bucks will no doubt make a counter move in Game 6, and Antetokounmpo will be taking a lot more than just 10 shots with the season on the line.

“I think Giannis is one of the most aggressive drivers in the game, trying to get downhill,’’ said Bucks interim coach Joe Prunty. “I think he gets bodied quite a bit. I’m concerned about how much they’re pushing.

“I want him to keep attacking, regardless of how physical the game may be, but in the grand scheme of things, I’ll just say it’s on all of us. In regards to finding better opportunities for shots, we have to make sure he’s getting the ball.’’

Smart, who provided a spark early and often in his first game since March 11 following thumb surgery, gives the Celtics second unit a boost, and that will be needed again.

The Bucks reserves provided offensive punch in the Game 5 comeback bid with Parker scoring 17 more points and Shabazz Muhammad dropping 11 points in 9:46.

“I know their bench had a huge impact on us in Games 3 and 4 and a huge impact (in Game 5),’’ said Stevens. “Parker and Shabazz Muhammad gave them a chance to come back into the game. That was a big reason why they were in that position.

“Bench play is incredibly important and that’s why when you’re figuring out who you want to start, I don’t want to lose (Marcus) Morris’ impact that he brings when he comes in the game. Adding Smart helps greatly because it’s another body you can throw out there and a guy that can really play.’’

He showed that in Game 5, helping to put the Celtics in a position to finish off the Bucks and move on to the 76ers with a win in Game 6.