'Very close': Federer's brilliant sportsmanship against Zverev

Roger Federer has been lauded for an incredible act of sportsmanship after hinting his opponent should challenge an incorrect line call.

Federer was up 6-5 in the first set of his Hopman Cup clash against Alexander Zverev on Wednesday night when the German's first serve was called out.

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Zverev looked towards Federer for his opinion about whether the call was correct, with the Swiss Maestro replying "close".

"How close?" asked Zverev. "Very close," replied the Fed with a big grin on his face, suggesting he thought the ball was in.

Zverev got the hint and challenged the call, with hawk eye revealing the ball was good, meaning Federer conceded the point as he was unable to return the ace.

Federer exchanges a sheepish look with Zverev. Image: Channel 7

"What a good sport Roger is", commentators said as the crowd cheered the brilliant display.

It was almost a carbon copy of a similar moment at the Hopman Cup last year when Lleyton Hewitt was the beneficiary of a similar display of sportsmanship from Jack Sock:

Federer couldn't be happier with his lead up to the Australian Open, despite losing to Zverev in three sets.

The former world No.1 is returning from six months on the sidelines following ankle and back injuries and believes his preparation for the opening grand slam of 2017 couldn't be any better.

Watch the Brisbane International and Hopman Cup LIVE on the screens of Seven including the 7Tennis App and PLUS7.

with AAP