Good afternoon and welcome to our coverage of day seven at the US Open.

WINNER! Kuznetsova is out. Cibulkova moves into a commanding 4-1 lead. Never really in any danger as she drops her racket before waving to the fans by converting on her fourth matchpoint with a 7-4 win in the tiebreak. She is through to the last eight after an epic victory. She deserves a lot of credit. She will play the winner of Sharapova or Wozniacki.

We head for the breaker after Kuznetsova holds with some ease. We are two minutes short of the two-hour mark out on Arthur Ashe.

Cibulkova is again punching the air. She is again only four points short of the last eight.

Difficult to predict how this match is going to unravel. Moments after Cilbulkova had the game in the palm of her hands, we are suddenly level.

Just when she looks as if she might be heading out, Kuznetsova finds a timely response. She breaks back immediately by saving TWO match points and is hanging on by her fingertips out there.

BREAK! Cibulkova will serve for the match. Kuznetsova struggling to handle the pressure and she drops serve for a second time.

Kuznetsova suddenly in a spot of bother out there. She drops a third straight game and really needs to discover some magic on serve or she is heading out.

BREAK! 22 shots in one rally in that game, but Cibulkova does not lose track of what she needs to do. She breaks back. We are all level again.

Still no full house on Arthur Ashe for the meeting of these women. This looks like a replica of the first set as Cibulkova reduces her arrears to 3-2. Kuznetsova remains a break up.

A third straight game for the Russian. She cements the break. How she would like another as an insurance policy.

BREAK! Like in the first set, Kuznetsova strikes first. Will it be the key movement of the set. Cibulkova wouldn't let go of the Russian in the first set.

Kuznetsova quick to restore parity. No such drama of double faults at key times there. She is level. Games on serve.

Cilbulkova has only beaten Kuznetsova once, but that came in their last meeting on a hard court in Sydney earlier this year. The Russian leads 3-1 on the head to heads, but that means nothing at the moment.

SET! Could be an upset on the cards. She hit 12 winners compared to Kuznetsova's 20, but she breaks for a second time to win the set. Quality stuff from the unfancied Slovak.

Cibulkova asks the question of Kuznetsova. She will need to hold serve to force the tie-break.

Kuznetsova levels when she needs it most. Back on serve. Looking good for a tie-break in this set.

Cilbulkova has looked down and out, but now she is one game from the first set. The story can be found in the stats. Kuznetsova has converted only one out of nine break points, while Cilbulkova has made one from four. Cibulkova needing a bit of treatment.

BREAK! Top marks to Cibulkova for hanging in there. This set could have been out of sight, but she refuses to buckle and is now level. We are back on serve. Wonder if that will place some doubt in the mind of the Russian.

Cibulkova hanging in there. She manages to prevent the former champion gaining another break. Kuztesova continues to lead by the odd game in seven.

Better game by Kuznetsova on serve. Holds without too many problems. She is looking to emulate her victory at this tournament in 2004.