Mercedes may have to impose team orders, says Wolff

By Alan Baldwin SPIELBERG, Austria (Reuters) - Mercedes boss Toto Wolff threatened to impose 'team orders' on Lewis Hamilton and Nico Rosberg, however unpopular the move, after yet another collision between the battling Formula One title rivals in Austria on Sunday. The team mates have clashed three times in the last five races -- in Spain, Canada and the Red Bull Ring -- as their championship duel heats up. Wolff said something had to change.