Nadal and Dimitrov face tough contests: Australian Open matches to watch on Day 7

Ahead of the seventh day of action at the Australian Open on Sunday, the first grand slam tournament of the 2018 tennis season, here are some of the main matches to watch out for. All times mentioned are UAE (+4 GMT). The full schedule for Sunday's play on the main show courts can be found here . Magdalena Rybarikova (SVK X 19) v Caroline Wozniacki (DEN X 2) Second match on Rod Laver Arena, likely to be 6-7am start This match is one between two very gritty players in the WTA circuit. Rybarikova made a quiet run to the Wimbledon semi-finals last year before being blown away by eventual champion Garbine Muguruza. The humble but straight-talking Slovakian is expected to fight every bit as hard as her opponent Wozniacki. But the Dane has been one of the most consistent players over the past year, and usually gets through the early rounds with minimum fuss to make it to the second week of a major. Wozniacki may be reminded by the fact the last time they met was in the first round of the 2014 US Open, which Wozniacki won to spark a brilliant run to the final. Rafael Nadal (ESP X 1) v Diego Schwartzman (ARG X 24) Third match on Rod Laver Arena, likely to be 9-10am start Nadal is usually generous, sometimes even effusive, when he talks about his rivals. Despite enjoying a 3-0 head-to-head advantage over his next opponent - Schwartzman - he talked about being wary of taking him on. Nadal called the Argentine "a very complete player" against whom there was a good chance of he might even lose. Indeed, Schwartzman has been in excellent form in the recent past. His game has evolved and as Nadal said, he has the ability to dictate terms from the baseline. If his match against Novak Djokovic at last year's French Open is any indication of his talent, Nadal will be up against a feisty opponent. Grigor Dimitrov (BUL X 3) v Nick Kyrgios (AUS v 17) First match of evening session on Rod Laver Arena, noon start The most fascinating match on Sunday, this one is just too close to call. On paper Dimitrov has the advantage: he has won twice and lost once against the Australian, and he has enjoyed one of the best seasons of his career. But the world No 3 will up against a local favourite who is the best upcoming player on sheer ability. The X-factor is Kyrgios's mindset. He may be brilliant and confident of his abilities but he is notorious for giving up when he is trailing his opponent. He has matured over the past year, but there can be no telling which Kyrgios will turn up. If he is in a good mood, the chances are he might be able to win. If not, Dimitrov will have him for dinner. Denisa Allertova (CZE) v Elina Svitolina (UKR X 4) Second match of evening session on Rod Laver Arena, likely to be 3pm start The player who seems most likely to go all the way and lift the title is Svitolina. One of the best players in 2017, the Ukrainian has the form to win on Sunday. She is also ruthless, judging by the way she defeated 15-year-old compatriot Marta Kostyuk in the previous round. Allertova may be relatively unknown to fans, but Svitolina is unlikely to have forgotten the fact she lost to her the only time they met, at Doha in 2016. A repeat of that result looks highly unlikely. Pablo Carreno Busta (ESP X 10) v Marin Cilic (CRO X 6) Second match on Margaret Court Arena, likely to be 6-7am start Since enjoying a memorable run to the semi-finals of the US Open last year, Carreno Busta has experienced a dip in form and fortunes. He somehow finds himself in the third round at Melbourne, but he is up against a very difficult opponent in Cilic. The Croat, who had a successful 2017 that saw him reach the Wimbledon final, has also struggled in 2018. How both players deal with the pressure to perform will make for interesting viewing.

Nadal and Dimitrov face tough contests: Australian Open matches to watch on Day 7

Fourth-round action begins in Melbourne as Wozniacki and Svitolina will also be seen in action