1. Andy Murray v Grigor Dimitrov (AO, R4)

A fourth round tie between Andy Murray and Grigor Dimitrov is the pick of the men’s matches on Sunday with huge opportunities for the winner with the loss of Roger Federer from the fourth quarter.  Although the scheduling has been dumbfounding at times this week, i’m happy that this is the late night match on Rod Laver Arena on Sunday.  I’m shocked that Kyrgios and Tomic haven’t made it onto RLA yet.  Murray’s had a drama-free first three rounds at this year’s Australian Open.  He is yet to drop a set with victories over Yuki Bhambri, Marinko Matosevic and Joao Sousa.  Dimitrov meanwhile, has dropped three sets en route to making the second week of the Australian Open.  He went the distance with Marcos Baghdatis, 4-6 6-3 3-6 6-3 6-3, finishing with a good old hug.  Two of Dimitrov’s best wins of 2014 came against Murray; in Acapulco, Dimitrov won a fabulous semi-finals en route to winning his first ATP 500 title and then thumped Murray at Wimbledon.  In their most recent match, Murray won 6-3 6-3 in Paris.  This time round, i’m backing Murray for the win…

Prediction: Murray d. Dimitrov in 4 sets

2. Nick Kyrgios v Andreas Seppi (AO, R4)

In the biggest shock of the tournament so far, Andreas Seppi beat Roger Federer in four sets, 6-4 7-6(5) 4-6 7-6(5).  Seppi had won just one set in ten previous matches with Federer.  On match point, Seppi produced an incredible pass after a tense fourth set tiebreak.  Federer had discussed in press that he had a bad feeling about this match, which was surprising to hear.  All the credit must go to Seppi for the biggest win of his career.  His clean and flat hitting frequently caught Federer off guard and he was fully deserving of his victory.  In an all-unseeded fourth round match, Seppi plays Nick Kyrgios.  I’m surprised to see Kyrgios make it so far as I thought he was struggling with a back complaint.  His draw has opened up like a beaut, but he’s still had to beat the players he as come up against.  A four set victory over Ivo Karlovic was his best offering of the week.  On paper, playing Seppi in a fourth round match at a Grand Slam is a dream.  However, the Italian was superb against Federer and has made a pretty decent start to the year having reached the semi-finals in Doha.  This is a real toss up for me; after such a monumental win, there could be a comedown for Seppi.  Furthermore, Kyrgios won their only previous match at the US Open last year in straight sets.  This is one match where I can’t make my mind up…

Prediction: Kyrgios d. Seppi in 5 sets