ATP World Tour Finals
Venue: O2 Arena, London Date: 22-29 November
BBC TV coverage: BBC Two, 22/28/29 November, 1430 GMT
Roddick injured his knee while leading 4-3 in the first set against Wawrinka
Andy Roddick's hopes of reaching the ATP World Tour Finals in London have been boosted as scans have revealed no surgery is required on his left knee.
The world number six withdrew from his second-round Shanghai Masters match against Stanislas Wawrinka on Tuesday.
MRI scans showed a mild ligament sprain, and Roddick is expected to make a "100% recovery" in time for London.
"Andy will rest and receive treatments and is expected to start activity in two to three weeks," said a statement.
If Roddick's recovery goes as planned, the American will be available for the Paris Masters, which starts on 8 November, with the Tour Finals to follow at the O2 Arena from 22 November.
With Roger Federer, Rafael Nadal, Novak Djokovic, Andy Murray and Juan Martin del Potro all having qualified for the eight-man season-ending finale, Roddick is among a number of players fighting to claim one of the three remaining slots.
He is currently sixth in the standings ahead of Fernando Verdasco, Robin Soderling, Fernando Gonzalez and Jo-Wilfried Tsonga.