ADVANCE FOR WEEKEND OF JAN. 11-12 - FILE - In this June 11, 2013, file photo, Andy Murray, left, is watched by his coach Ivan Lendl as he plays a return during a training session at the Queen's Club grass court championships in London. Novak Djokovic and Roger Federer witnessed Murray's breakthrough successes after hiring Lendl as coach, so they have also turned to some past Grand Slam champions for help in 2014. (AP Photo/Kirsty Wigglesworth, File)

ADVANCE FOR WEEKEND OF JAN. 11-12 - FILE - In this June 11, 2013, file photo, Andy Murray, left, is watched by his coach Ivan Lendl as he plays a return during a training session at the Queen's Club grass court championships in London. Novak Djokovic and Roger Federer witnessed Murray's breakthrough successes after hiring Lendl as coach, so they have also turned to some past Grand Slam champions for help in 2014. (AP Photo/Kirsty Wigglesworth, File)