World champion Valentino Rossi qualifies sixth for Sunday 's U.S. Grand Prix . Italian retire with mechanical problem in second race back after breaking his leg . MotoGP leader Jorge Lorenzo claims fifth consecutive pole position this season . ` My hope for tomorrow is to be able to finish the race without too much pain and to do the best we can in the circumstances . Spaniard edged out 2007 world champion Casey Jones with fast penultimate lap .
World champion Valentino Rossi qualifies sixth for Sunday 's U.S. Grand Prix . Italian retire with mechanical problem in second race back after breaking his leg . MotoGP leader Jorge Lorenzo claims fifth consecutive pole position this season . Spaniard edged out 2007 world champion Casey Jones with fast penultimate lap .