One of the biggest challenges Derek Fisher faced as a first-time coach last season was determining a regular Knicks lineup. That hasn’t been an issue this season, at least not until this week.

Fisher used the same starting lineup 34 times during a stretch of 38 games, and the Knicks won 18 of those games. But injuries and illness forced starters Carmelo Anthony, Kristaps Porzingis and Jose Calderon to miss Thursday night’s game against the Raptors, and the second-year coach again had to mix and match.

“We had a really good run going and kind of got hit by some untimely injuries and some things, but we still had chances to win these games,” Fisher said. “Can’t make excuses for the guys that are playing. We have to focus on doing the things that you still can do when you’re out there.”

Anthony missed two games with a sprained ankle, returned for four games, missed two games with left knee soreness and returned Friday night against the Phoenix Suns. Porzingis was back after missing Thursday night’s game with an upper respiratory illness. But reserve Langston Galloway remained in the starting lineup for the second straight game because Calderon still was out with a groin injury.

“It changes things,’’ Fisher said, “but I think in all ways, every team faces it at some point in the season.”

Calderon tested his injured groin on the court before the game but was not able to play. “With the groin injury, you can do some controlled movements and feel OK, but obviously, the game is not controlled,” Fisher said. “He’s still at a point where he’s not able to go.”

Knicks add Antetokounmpo

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The Knicks signed Thanasis Antetokounmpo to a 10-day contract. Antetokounmpo, chosen by the Knicks in the second round of the NBA Draft in 2014, has spent the last two seasons playing for their D-League team in Westchester.

“Wherever I can fit to stay here,” he said. “Whatever the team needs me to do . . . I just want to be here.”

When asked if Antetokounmpo has developed since the Knicks last saw him firsthand in training camp, Fisher said, “We’ll find out if he gets in the game. That’s the only time you can really tell if a player has grown.”