Roger Federer’s participation in the Montreal Masters starting a week from Monday remained in doubt on Friday due to back pains which also contributed to an opening loss at the Suisse Open.

“In the last 7-10 days I could hardly practise, this made it difficult to prepare properly. I decided to play so it’s no excuse,” the 17-time grand slam champion said after a straight-set second-round loss on Thursday to German Daniel Brands.

The Swiss tennis icon was competing in his home event for the first time since winning it nine years ago. The pain — which Federer said started last week in Hamburg and forced him to take anti-inflammatories on the way to the German semi-finals — casts uncertainty on his US Open preparation programme.

Federer admitted, “My presence in Montreal is far from assured. I first need to take care of my back. It is a serious injury. The pain is less than Indian Wells (last March). But I will have to heal through exercises and treatment.”

The world number five — his lowest ranking in a decade — will only make a late decision about travelling to Canada with a month to go before the August 26 start of the US Open.

His last three losses at Wimbledon, Hamburg and Gstaad have been among his worst in a decade and a half — losing to a pair of opponents outside the ATP top 100 (Sergiy Stakhovsky at Wimbledon; Federico Delbonis in Hamburg) as well as the 55-ranked Brands.

“I will have to do a lot of exercises and see how it all feels. My main priority now is to fix my back. I would love to be able to train at 100 per cent,” said Federer, whose only title in 2013 came at Halle last month.

“I’ll have to see if the rehab is enough to let me play in Montreal. If it is, I’ll go. If not, then it gives me another week.”

Federer, whose last grand slam title was at Wimbledon 2012, is also due to play the Cincinnati Masters — the final major tune-up for the grand slam in New York.

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