Davis Cup: Janko Tipsarevic vs. Juan Martin Del Potro

Janko Tipsarevic goes in as favourite against Juan Martin Del Potro in the second rubber of Serbia's Davis Cup semi-final with Argentina.

This is the must-win clash for Argentina but Del Potro will be going in as a slight underdog after Tipsarevic's brilliant form over the past month. It's taken him to a new career high of 13 and on the brink of the top ten.

He was the first man to test Novak Djokovic in New York, pushing his friend mighty close for two sets and if he reproduces that level today, Del Potro will have to find his 2009 form to stand a chance.

After an encouraging display at Wimbledon, the hard court swing has been desperately disappointing for Del Potro. He made early exits at both Masters 1000 events and lost out in the last sixteen at Flushing Meadows to Gilles Simon.

However Del Potro has won both his previous matches with Tipsarevic and denied the Serb a first ATP title in Delray Beach this year, beating him 6-4, 6-4 in the final. Tipsarevic though, does have that tendency to find an extra level when it comes to the Davis Cup. He saved his country this time last year, beating Tomas Berdych and then winning a decisive final rubber against the Czech Republic to see his country through to the final.