Courtney Lee apologized to the Knicks fans who showed up Monday at Madison Square Garden to watch the home team roll over against the lowly Lakers in the boo-infested 121-107 defeat.

“[Monday] night that effort was pretty bad, man,’’ Lee said. “I definitely got to apologize to the fans who spent hard-earned money to watch us play. We definitely didn’t show up to compete at the level we needed to win the game, especially in the situation we’re in.’’

A fuming Jeff Hornacek threatened a “battle practice’’ for Tuesday and it lived up to the hype. Lee said the session became “chippy’’ with “multiple flare-ups’’ during 80 minutes of nonstop scrimmages.

“Today was much-needed,’’ Lee said. “We got after it today. Guys were pushing each other. It got a little chippy. That’s what we needed.

“Multiple flare-ups, guys getting annoyed with each other. Guys being into guys. Guys voicing their opinions, but also competing against each other. Me trying to score on you, you trying to stop me.”

Hornacek, who ripped the team Monday night for its lack of pride and effort, was pleased with what he saw, saying the scrimmages got extra physical because few fouls are called in such sessions.

“Hopefully things that were said, things we did today, it’s a tough game to come back against the Clippers, [but] let’s see the battle,’’ Hornacek said. “If you battle, do a lot of things at practice today and come out on the short end you can live with that. When you don’t it becomes discouraging.’’

The Knicks defense was soft against a young Lakers club that had lost 12 straight road games. The Lakers had their way in the paint as they built a 27-point lead in the second quarter, and the Knicks rotations were wretchedly slow.

“We had a lot more [effort] today than we did last night,’’ Hornacek said of the session. “Sometimes it takes a few practices to get them into that mentality of: ‘We got to go harder.’ ”

Knicks president Phil Jackson watched the practice but saved his messages for Twitter with an indirect hit at Carmelo Anthony. Lee said the team didn’t need a Zen Master speech.

“At this point, we don’t need any more pep talks,” Lee said. “We don’t need any more pats on the back. None of that stuff. It’s now or never if you don’t realize that as a player, you’re in the wrong sport and the wrong team. We need it now.’’