How high do you think tennis player Kei Nishikori, currently ranked No. 5, can go in world rankings?

He's very talented. I think top three.

One can only speculate, but his coach, Michael Chang would be ecstatic to see Kei Nishikori peak at World No 2. like he did back in his own heydey. WTA tour rankings are based on a rolling 52 week system using a player's best 17 results for singles over the past 12 months.

WTA tour rankings are based on a rolling 52 week system using a player's best 17 results for singles over the past 12 months.

Probably true, but, can I ask, is Nishikori a woman?

If Kei can concentrate on winning, 1000's series, hasn't done yet, and going deep in the slams as he just did at the US open, the ranking will take care of itself..

He can't seem get over that hump of winning a grand slam event. Until he does that, the highest he can go is probably 4, but he's young and still has plenty of chances to win a big one.

Is incredible he has stayed at around number 5 for 2 years now without having a stronger serve. I have always thought players should only have one serve each as a constant flow of aces and faults ruins the game. Cannot see Nishori rising above number 4

I really hope he does. If he does, or doesn't has no bearing on my choice to cheer him on ! Ganbarre, Kei-san

It's the usual 'Big In Japan' syndrome.

For Japanese sportsmen they only have to show a glimmer of international success, and be the best in Japan and, through sponsorship and adverts, they're financially made for life.

While Japanese sportswomen have to be the best in the world to have the same financial set-up.

The result has been that some Japanese sportswomen are truly up there, by international standards, while Japanese sportsmen usually don't rise any higher than' better than the international average'. I've seen this time after time over the last 20 years, with Nakata (soccer) to Ryo chan (golf), to name but 2.

If Kei concentrated on his tennis, instead of advertising everything from anal lubricants to uniglo, then he might rise higher, but he won't and number 5 is as high as he will go and that will last for only one year.

Depends on the other players, 3 I think probable at some point, 2 or 1 less so but not inconceivable. I agree with this guy:

NOVAK DJOKOVIC: Well, Kei is in form, and winning bronze in Rio, playing finals in Toronto, and winning here against Andy Murray who was in tremendous form for last couple of months. Kei is now very established, top 5, top 7 player in the world for last couple of years. He's always there. He played in US Open finals; he won against me in semis that year. He also doesn't really get too frightened by the big occasion. He's actually looking forward to play the big matches. He's very committed daily. You can always see him in the gym or the practice courts. Michael Chang is there. He's got a full squad of experts around him to, you know, to perfect his game. It's good to see that. He's the best Asian tennis player in history of Asia. He's got a lot of support. Yeah, he's hungry for success, no doubt. He's never won a Grand Slam but he's always there. You know, he's very close.

5 is his peak.