TORONTO - The NBA pre-season can seem numbingly long, but the Toronto Raptors still have plenty of work to do before the curtain comes up on the regular season next week.

Coach Dwane Casey spent Tuesday's practice session in teaching mode. At the top of his agenda: defence. Again.

The Raptors are 5-1 on the pre-season, but have yet to put in the solid defensive effort — especially on the boards — that Casey would like to see before opening-night tipoff.

"I want to start the real season but we're still in practice mode, we've got to fix some things," said centre Jonas Valanciunas, who led the Raptors in rebounds last season. "(Rebounding) is an area we've got to get better on. We're doing that every practice, so hope we're going to get better and we're going to show better results.

"We've got to get used to going for the ball, all five guys."

The Raptors were a disappointing 20th in the NBA last season in defensive rebounding.

The 22-year-old Valanciunas will be counted on to anchor Toronto's defence. However, despite going into his third NBA season, the Lithuanian still has a lot to learn before he has a complete grasp of the nuances of the NBA game.

Valanciunas played in Los Angeles last summer before going to Spain for the FIBA World Cup, where he led the tournament in shooting percentage at 69.6 per cent.

"But one summer is not enough, he needs to continue to go with Hakeem (Olajuwon, former Raptor and Hall of Famer) or whoever in the summer," Casey said. "He needs to play pickup basketball where it's not as organized or you really have to anticipate against quicker athletes, maybe smaller athletes, so it's a work in progress for him."

Valanciunas could be one of the more comfortable Raptors when the team hosts Maccabi Haifi at Air Canada Centre on Wednesday. The team plays in the Israeli Basketball Super League, winning the Super League championship in the 2012-13 season — its first Israeli title since the team was formed in 1953.

"It's a good test for us, they play a different style, mostly four out and one in, really spread the floor, a lot like four guards out there on the floor," Casey said. "So it's going to be a challenge for Amir (Johnson) and Tyler (Hansbrough) and the big fours (power forwards) to get out there and guard those guys off the bounce, off the dribble, getting back in transition.

"It will be a challenge for us. They play faster up and down moreso than we're used to and a tremendous amount of pick and rolls, a lot like what San Antonio did with four ball-handlers with the ability to run a pick and roll, which is a little different than what you see in the NBA."

Maccabi Haifa, which is owned by American businessman Jeffrey Rosen, was beaten 91-59 by the Kings on Sunday. They'd arrived in Sacramento following a 10-hour bus ride from Portland, where they lost 121-74 to the Trailblazers.

Three players remain in the running for the 15th and final spot on the Raptors roster — centre Greg Stiemsma, point guard Will Cherry and swingman Jordan Hamilton. NBA rosters have to be set by opening day on Oct. 27.

"I think it makes it tough on management because we all can play, we're good players," Hamilton said. "Will's a good young guard, I feel like I can score, and Greg, he does all the intangibles. Best man wins."

The Raptors open the regular season Oct. 29 against the visiting Atlanta Hawks.