US Open Tennis 2015 Results: Scores, Highlights, Reaction from Tuesday Night

Serena Williams made it one step closer to a first calendar Grand Slam on Tuesday as she overcame her sister Venus 6-2, 1-6, 6-3 in the U.S. Open quarter-finals.  

World No. 1 Novak Djokovic also made it through to the last four in the men's draw as he defeated Spain's Feliciano Lopez 6-1, 3-6, 6-3, 7-6(2) in sweltering heat.

The Serb will now meet Marin Cilic in Friday's semi-finals after the defending champion beat Jo-Wilfried Tsonga in five sets. Meanwhile, Williams must get past the unseeded Roberta Vinci if she is to make the final.

Here's a look at the singles results from Tuesday's action along with a closer examination of the two headline matches of the day.

Women's Singles
Men's Singles
Result	Score
Roberta Vinci (ITA) def. Kristina Mladenovic (FRA)	6-3, 5-7, 6-4
No. 1 Serena Williams (USA) def. No. 23 Venus Williams (USA)	6-2, 1-6, 6-3
Result	Score
No. 9 Marin Cilic (CRO) def. No. 19 Jo-Wilfried Tsonga (FRA)	6-4, 6-4, 3-6, 6-7(3), 6-4
No. 1 Novak Djokovic (SRB) def. No. 18 Feliciano Lopez (ESP)	6-1, 3-6, 6-3, 7-6(2)

Serena Marches on Despite Venus Test

It is safe to say that no athlete has dominated a single sport in 2015 quite like Williams has women's tennis.

She has been dominating the sport for over a decade, but in the current season, she has won the three major tournaments going and is on the verge of becoming the first winner of a calendar Grand Slam since Steffi Graf in 1988.

A victory at Flushing Meadows this year would take her Grand Slam singles title tally to 22, tied with the legendary Graf and two back from Margaret Court's record haul.

However, she was given a scare in her pursuit of the perfect year by Venus, who bounced back impressively from losing the first set to force a decider.

Serena looked on course to blow her sister away as she took the first set in clinical fashion; however, nerves seemed to get to her in the second, and she double-faulted to go 3-1 down and could never recover.

Older sister Venus, 35, claimed the momentum and forced another break before serving out the second set 6-1.

Serena, though, showed why she is such a tremendous champion as she came roaring back in the third set, the crucial break coming early for the world No. 1 as she overpowered her sister with some immense backhand winners.

Gracious in defeat, Venus offered up an assessment of her sister which is hard to argue with, per the Daily Telegraph:

Serena now faces world No. 43 Vinci in the last four and is a heavy favourite to reach the final. If she makes the last two, it will likely be Simona Halep or Petra Kvitova that stands in the way of the American and an astounding calendar Grand Slam.

Djokovic Made to Toil by Lopez

Djokovic has his own chance to make history at the U.S. Open and join the elite group of seven men to have won 10 or more Grand Slam titles.

He made it through to the semi-finals on Tuesday, but he was not given an easy night's work by Lopez.

The 2011 U.S. Open champion breezed through the first set against the 33-year-old but came unstuck in the second as Lopez levelled with a 6-3 triumph. Djokovic was not happy and took his frustration out on his tennis bag, per BBC Sport's Piers Newbery:

However, as is so often the case with Djokovic, he was able to wrestle back the momentum and keep his head.

He re-established control from the off in the third set, and although Lopez put up an admirable fight in the fourth to force a tiebreak, the world No. 1 eventually prevailed.

But it was an awkward evening for Djokovic, and he admitted as much after the match, per BBC Sport's Newbery: "He's one of the rare players that actually serves volleys on the first and second serve. I'm just glad to get through in four. Obviously, it was frustrating at times but this is quarter-finals of a Grand Slam, this is what you expect."

Djokovic does not have the best of conversion records in New York despite having reached the last four on a number of occasions, per BBC Sport:

"

Still the favourite? Novak Djokovic has reached his ninth straight #USOpen semi final. He beats Lopez in four sets. pic.twitter.com/x5sqjOtc8N

— BBC Tennis (@bbctennis) September 9, 2015"

However, only a brave punter would bet against him picking up a second U.S. Open title in 2015, even with defending champion Cilic standing in his way in the next round.