Guide to seeds' rivals at US Open

Top guns face some tricky opponents in first round at Flushing Meadows

AFP Sport's guide to some of the players hoping to cause first-round upsets at the US Open which gets underway at Flushing Meadows on Monday:

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Novak Djokovic vs Diego Schwartzman

First meeting

Top seed and 2011 champion Djokovic has reached the last four US Open finals but has never played the world No 80 Argentine before. The 22-year-old 5ft 7in (1.70m) player from Buenos Aires has played just five matches on the main tour this season but qualified for the French Open where he lost to Roger Federer in the second round. His first-round win over Gastao Elias in Paris is his only Grand Slam match victory. He is making his debut at the US Open having lost in qualifying in 2013.

Roger Federer vs Marinko Matosevic

Federer leads 1-0

Australian world No 77, the Bosnian-born Matosevic is nicknamed 'Mad Dog' and caused a stir at Wimbledon this year when he criticized Andy Murray's decision to hire Amelie Mauresmo as coach. The 29-year-old has endured a miserable relationship with the US Open, losing in the first round on all three visits.

Andy Murray vs Robin Haase

Murray leads 2-1

The 27-year-old Dutchman Haase is ranked 70 after reaching a career high of 33 in 2012. Hasn't played in the US hard-court buildup to the Open, being sidelined since a first-round defeat on the Kitzbuhel clay four weeks ago. Has never got beyond the third round of a major in his nine-year career and has won just one match at the US Open - in 2011 before losing to Murray in a five-set thriller in the second round.

Stan Wawrinka vs Jiri Vesely

First meeting

Vesely, the 21-year-old Czech left-hander, is one of the sport's highest-regarded younger players, named the ATP Star of Tomorrow in 2013 after he had started the season at 250 in the world. Now at 76 in the rankings, he has helped the Czech Republic reach the Davis Cup semifinals this season and made the third round at Wimbledon. Made his US Open debut in 2013 but lost in the first round.

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Serena Williams vs Taylor Townsend

First meeting

Five-time champion Williams is 32 now and faces 18-year-old US compatriot Taylor Townsend for the first time. Ranked 103rd, Townsend is match-tough, having made the second round in Washington - where she was runner-up to Eugenie Bouchard in 2013 - and Cincinnati in the hard-court season. Also made the third round at the French Open. The tough left-hander lost in qualifying at the US Open the past two years.

Maria Sharapova vs Maria Kirilenko

Sharapova leads 5-2

The battle of glamorous 27-year-old Russian blondes, former childhood friends, will ensure a busy night for photographers. Kirilenko, a former world No 10, is down at 113 after an injury-plagued season which has seen her play just six tournaments and saw the end of her engagement to Russian ice hockey star Alex Ovechkin. Sharapova and Kirilenko once played doubles together, winning a title on grass in Birmingham in 2004 on the eve of Sharapova's breakthrough Wimbledon title.

Simona Halep vs Danielle Rose Collins

First meeting

Collins, 20, has not featured on the tour since 2012 and her last world ranking was recorded at the end of 2011 when she stood at 608. She has never played a main tour match. Since 2012 she has played at national and state-level tournaments and reached the US Open as a wild card after winning the NCAA collegiate championship. Her career earnings are $4,964 compared to second-seeded Halep's $5.3 million.

Petra Kvitova vs Kristina Mladenovic

Series level 1-1

The 73rd-ranked Mladenovic has enjoyed Grand Slam title success, winning the mixed doubles at Wimbledon in 2013 and this year's French Open with Daniel Nestor. Made the third round of the US Open singles in 2012 where she lost in straight sets to compatriot Marion Bartoli.