Norman: Stan needs to me more consistent

US Open winner Stan Wawrinka needs to be more consistent to go up to the next level according to his coach Magnus Norman.

The 31-year-old Wawrinka has been coach by Swede Norman since 2013 and together have won three grand slam singles titles, the 2014 Australian Open, 2015 French Open, and the 2016 US Open, ending significant losing streaks against Rafael Nadal and Novak Djokovic as well as earning rare wins over Swiss compatriot Roger Federer. 

In an interview, Norman acknowledged the one problem with his charge was that Wawrinka was very up and down in 2016, losing in the Australian Open third round and in the second round at Wimbledon along with several other upsets in tournaments.

"[He's] very much up and down and that's something we work on every day, more or less every day," Norman said. "Still haven't found really the key, [the way] he can be a little bit more consistent. But when he's on, when he's playing a lot of matches, I think he's tough to beat."

Norman added that he felt that world number three Wawrinka had the weapons, when he was on-song, to defeat world No.1 Djokovic more often just like he did in the US Open final recently.  

"Stan is one of the few who can really hit through Novak if he has a good day. Even if I think of this tournament (US Open), Stan played a little bit differently than other grand slams. 

"He played with a little bit more margin, a little bit more defensively. That's something we talk about," he added.