 Complete the following phrase:  His best performance in a Grand Slam was making the semifinals of the 2009 Australian Open, where he lost to compatriot and eventual champion Rafael Nadal in five sets. The match itself has been considered one of the greatest Grand Slam semifinals of all time. Verdasco has also reached the quarterfinals twice at the US Open, in 2009 and 2010, losing to Novak Djokovic and Rafael Nadal respectively, the latter of whom went on to win the title, and once at the 