Organisers of the ATP World Tour Tennis Finals in London next month will be keeping a close watch on Rafael Nadal's health over the next couple of weeks.
The already-qualified Nadal has been diagnosed with appendicitis and question marks remain over his appearance.
There's also a concern about the home favourite Andy Murray whyo is one of several players scrambling to accumulate enough points to fill one of the three remaining spots in the 8-man field at the hugely popular event.
Murray plays in Valencia this week while Nadal is in Basel, having admitted that he is struggling top rediscover his health and form.
Apart from Nadal, others already qualified for the World Tour Finals are Roger Federer, Novak Djokovic, Marin Cilic and Stanislas Wawrinka.
Meanwhile Andy Murray has come from a set down to beat David Ferrer in three sets in the final of the Vienna tennis Open, moving ahead of the Spaniard in the race to qualify for the World Tour Finals.
Murray broke serve three times in the deciding set on the way to only his second title of the year and he's 7th in the race to London.
It was the Scot's first win over a top-8 player since he won Wimbledon last year.
Andy Murray moved into eighth place in the race to the ATP season finals on Saturday as he reached the Austrian Open final with a 6-4 6-3 win over qualifier Viktor Troicki.