Who Are You? Guide to Seeds Rivals at US Open

AFP Sport's guide to some of the players hoping to cause first round upsets at the US Open which gets under way at Flushing Meadows on Monday (Head-to-head -- year, tournament, surface, round, winner, score):

MEN

Novak Djokovic v Diego Schwartzman

First meeting

- Top seed and 2011 champion Djokovic has reached the last four US Open finals but has never played the world number 80 Argentinian 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. Is making his debut at the US Open having lost in qualifying in 2013. (Read: Gluten-Free India Ready to Welcome Novak Djokovic!)

Roger Federer v Marinko Matosevic

Federer leads 1-0

2014 Brisbane Hard QF Federer 6-1, 6-1

- Australian world number 77, the Bosnian-born Matosevic is nicknamed "Mad Dog" and caused a stir at Wimbledon this year when he criticised 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. (US Open: Yuki, Sanam Lose, No Indian in Singles Event)

Andy Murray v Robin Haase

Murray leads 2-1

2013 Australian Open Hard R128 Murray 6-3, 6-1, 6-3

2011 US Open Hard R64 Murray 6-7 (5/7), 2-6, 6-2, 6-0, 6-4

2008 Rotterdam Hard R32 Haase 7-5, 6-3

- 27-year-old Dutchman Haase is ranked 70 after reaching a career high of 33 in 2012. Hasn't played in the US hardcourt build-up 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. (Also Read: Djokovic Could Face Murray in US Open Quarters)

Stan Wawrinka v 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 semi-finals this season and made the third round at Wimbledon. Made his US Open debut in 2013 but lost first round.

Serena Williams celebrates her victory.

© AFP

WOMEN

Serena Williams v 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 hardcourt season. Also made the third round at the French Open. The tough, left-hander lost in qualifying at the US Open in the last two years.

Maria Sharapova v Maria Kirilenko

Sharapova leads 5-2

2005 Los Angeles Hard R32 Sharapova 7-6 (9/7), 6-2

2005 Beijing Hard SF Kirilenko 6-4 2-1 - retired

2006 Miami Hard R16 Sharapova 3-6 6-4 6-1

2010 Australian Open Hard R128 Kirilenko 7-6 (7/4) 3-6 6-4

2012 Indian Wells Hard QF Sharapova 3-6 7-5 6-2

2012 Olympics/London Grass SF Sharapova 6-2 6-3

2013 Indian Wells Hard SF Sharapova 6-4 6-3

- The battle of glamorous 27-year-old Russian blondes, former childhood friends, will ensure a busy night for press photographers. Kirilenko, a former world number 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 2004 on the eve of Sharapova's breakthrough Wimbledon title.

Simona Halep v Danielle Rose Collins

First meeting

- Collins, 20, hasn't 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 had reached the US Open as a wildcard after winning the NCAA collegiate championship. Her career earnings are $4,964 compared to second-seeded Halep's $5.3 million.

Petra Kvitova v Kristina Mladenovic (FRA)

Series level 1-1

2008 Paris Carpet Q-R32 Kvitova 6-3 6-2

2013 Paris Hard QF Mladenovic 6-3 6-4

- 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.