Andy Murray has a tricky opening match in Cincinnati this evening against Russian Mikhail Youzhny.
Murray's preparation for his US Open defence got off to a terrible start last week in Montreal, when he lost his second match to Ernests Gulbis.
He could have been facing the unpredictable Latvian again in Ohio, but Youzhny beat him in their first round match.
Something of a veteran of the tour at 31, Youzhny has never beaten Murray, though they have only ever met three times.
Their last encounter was at Wimbledon this year where Murray won in straight sets, and their only previous hardcourt meeting was back in 2007 where the Scot won.
Youzhny is currently ranked 25 in the world, and is one of those players that can blow hot or cold. On his day, he can be brilliant, but it depends which side of bed he gets out of.
He had a dreadful start to the year, barely able to string two victories together, but he got up and running at the French Open where he reached the fourth round.
He reached the final on grass at Halle, losing to Roger Federer in the deciding set, and bowed out to Murray in the fourth round at Wimbledon.
After a first round exit on the clay of Hamburg, he won the Gstaad tournament, but in Montreal last week he fell victim to Milos Raonic.
Youzhny is an all-court player, happy at the net and the baseline, and his main weapon is his backhand.
His backhand slice, in particular, is one of the best on the tour, and when he drives his backhand it goes like a bullet.
Unless Murray plays much better than last week, he could be in for a tough match.