Cuban was none too happy with Nowitzki's effort in recent games, in particular his defense and rebounding. Cuban also isn't happy that this is a regular thing.

“I think sometimes he loses concentration, and I think we’ve got to get past that,” Cuban said Monday, according to the Fort Worth Star-Telegram. “I mentioned it to him (Monday). I asked him how his nap was during the game (Sunday vs. the Oklahoma City Thunder). He laughed. At least that’s while I was facing him. When I turned my back and walked away, I don’t know.”

Cuban said it's clear when Nowitzki has hit the snooze button early in a game.

“You know when Dirk’s trying to get 10 rebounds, and you know when he’s not," Cuban told the Star-Telegram. "And we need a little bit more of those try-to-get-10 games because I think our starters in particular respond to his energy.”

Nowitzki kept his response low-key.

"I've got to compete and help the guys set the tone," Nowitzki told the Star-Telegram after a Mavs' victory Monday night. "Some nights that's defensively or on the rebounding, some nights it might be more scoring.

"I usually take pride in being a good all-around player. Especially in this homestand, if we want to make the playoffs we've all got to do a little more."