Coach Jon Scheyer is stressing improvement with his No. 9 Duke team, even if that means some challenging discussions with the Blue Devils.This is the time for them to make notable upgrades, and there’s another chance for that when La Salle visits Tuesday night in Durham, N.C.”We have good guys that want to be coached, that want to be pushed,” Scheyer said. “And so, it’s up to us to challenge them and to do that every day. And so, they’ve responded in every game, because I haven’t been necessarily the most positive after these games. I’ve been very honest.”Duke (3-1) won twice last week by defeating Michigan State and Bucknell.La Salle (4-0) has won its first four games for the first time since the 2014-15 season.”It’s nice to be where we are going into just a great opportunity for us going to Duke,” La Salle coach Fran Dunphy said. “We don’t have that much margin for error.”Scheyer continues to assess different player combinations with the Blue Devils.”There’s the chemistry,” he said. “There’s the continuity that we’re trying to develop.”Jared McCain turned in Duke’s first double-double of the season with 17 points and 10 rebounds in Friday’s 90-60 victory against Bucknell. That was combined with sophomore forward Mark Mitchell’s career-high 20 points.”We have a lot of different players on this team, a lot of different scoring power,” Mitchell said. “We can hit you different ways on different nights.”Duke preseason All-American forward Kyle Filipowski exited late in the first half with an ankle injury. He returned briefly in the second half but wasn’t needed and totaled just 17 minutes of playing time. Scheyer said he will monitor how Filipowski’s ankle responds leading up to the La Salle game.The Explorers survived Saturday’s 79-78 home triumph against Southern Indiana, boosted by Khalil Brantley’s career-high 30 points.