Postpublished at 09:44 Greenwich Mean Time 26 January 2015
It's all too easy for Radwanska in this game, the Pole cruising through for the loss of just a single point. It's Williams who now looks a bit lost.
Top seed Novak Djokovic beats Gilles Muller 6-4 7-5 7-5
Serb reaches quarter-finals without dropping a set
Venus Williams through to first Grand Slam quarter-final since 2010
She beat sixth seed Agnieszka Radwanska 6-3 2-6 6-1
Serena, Wawrinka, Raonic & Nishikori also through
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Aimee Lewis and Lawrence Barretto
It's all too easy for Radwanska in this game, the Pole cruising through for the loss of just a single point. It's Williams who now looks a bit lost.
Radwanska looks like she's found a rhythm on her returns and rustles up two break points. Williams has a golden opportunity to put a smash away, but hits wide and Radwanska gets the break. The pendulum looks to have swung the other way. How will Williams respond?
Radwanska gets that sinking feeling as she watches a Williams lob glide over her head and drop in to bring up 0-30. The Pole is soon facing two break points, the first of which is saved as Williams hit long. The second is saved in better fashion, courtesy of a very timely ace. Deuce.
Radwanska battles through the next two points, helped hugely by her first serve returning to form, to seal her first game in what feels like forever.
That sitdown at the change of ends has clearly done Radwanska the world of good with the Pole coming out and rustling up her first break point of the match.
Williams saves it and does the same with two more before manufacturing a game point - but she goes too big and we're back to deuce. Just the nine minutes for this game so far...
Three minutes later and Williams manages to string two points together to win the game - her fifth in a row. It hasn't been as easy as that stat suggests, but the American is winning all the close games.
Eighth seed Milos Raonic came through an intense tussle against Spain's Feliciano Lopez on Hisense Arena. The Canadian beat the 12th seed 6-4 4-6 6-3 6-7 (7-9) 6-3, smashing 30 aces and 81 winners, to reach the quarter-finals where he will face the winner of Novak Djokovic and Gilles Muller.
Lopez saved two match points during the fourth-set tie-break, incredibly that was the third match in a row he has saved a match point.
That first set lasted 51 minutes, with most of the time spent on that marathon seventh game. It was Williams who was the more aggressive and consistent, clocking up 10 break point opportunities to Radwanska's 0.
Williams headed the winners tally 20 to 10 and won 47% of the receiving points, compared to just 18% for Radwanska. Can Williams take this form into the second set?
Dangerous times for Radwanska, whose first serve is falling apart. The Pole looks a bit lost out there and soon finds herself at 15-30.
Radwanska battles back in the next couple of points, but Williams forces deuce. Oh dear. We've been here before...
Williams hits a forehand that glues itself to the line and though Radwanska pokes it back, the American whips it away for set point.
But it's agony for Williams as she jumps too early for a smash and makes a hash of it. A second and third set point slip by but she will not be denied a fourth. Williams takes the set - and deservedly so.
That's exactly what the Williams team doctor will have ordered, a nice quick service hold after a marathon sixth game. Williams drops just one point to consolidate the break and move to within a game of the first set.
On we go, another break point saved - and that's followed up with a game point for Radwanska. But Williams will not let this go.
Despite being dragged around the court, Williams picks everything up, finishing the point with a lovely backhand volley for deuce.
Radwanska's forehand lets her down for another break point, but Williams again fails to take it. Does anyone want this game?
A sixth break point for Williams! And at last she takes it! Just the 30 points to win that game, then. Crikey.
Williams goes after the Radwanska second serve and gets her reward for 15-15. The American then hunts down a short ball and punishes it to put some pressure on the Pole's serve.
But two unforced errors - her sixth and seventh of the match - swing the momentum back to Radwanska, who promptly throws it a way with a tame forehand. Deuce.
A break point - the first of the match - is Williams' for the taking, but she wastes it with an error on her forehand. No bother, though, as the American attacks the Radwanska serve, which is starting to falter, once more and is rewarded with a break point.
It goes wanting, Williams' screeching in frustration as she dumps a forehand pass in the net - she knows the opportunity was there for the taking. Deuce again.
Bit of a change-up from Williams, who takes the pace off the ball and whips it cross-court, forcing Radwanska to the net. The Pole doesn't deal with it well, dumping the ball in the net. Before she knows it, Williams has 40-0 on the board and the game is hers when a stretching backhand from Radwanska drifts long.
Blink and you'll miss it, Radwanska blitzes through her service game to love for her first comfortable hold of the match.
Williams' hard and heavy approach to her hitting is working at the moment, with only the odd mistake creeping in.
Radwanska is covering the court well, but just struggling to deal with the power at the moment. Williams holds. It's a fine start to what could very well turn into a very tasty contest.
Radwanska conjures up some magic with a delicate drop shot which leaves Williams scrambling. The American gets to it, but it's an easy put away for the Pole to bring up 30-0.
But back comes Williams, with her contrasting style of hitting the ball hard - very hard. The American steps inside the baseline, controlling the next two points and we're level at 30-30.
A loose shot from Williams, followed by an angled forehand into the corner, which Williams chooses not to chase down, and it's a hold for Radwanska.
A lengthy rally gets us under way in the first point on Venus' serve, with the American timing the ball well. Unfortunately, Venus can't get the depth and Radwanska bides her time before hammering a forehand down the line.
An overrule from the umpire leaves Radwanska fuming, but hawk-eye shows it was a good call. Venus ploughs on, battering a forehand into the corner to close the game out to 15. Big, big hitting from the American.
Venus' tactics are clear. She's going after this match early doors, rushing to the net when she can in an attempt to keep the points short. The results are mixed, and despite forcing Radwanska to deuce, the American concedes the game.
The warm-up is over. There's just time for one final sip of water and a wipe of the towel before we get this fourth round match under way. Radwanska to serve. Let's do this.
Agnieszka Radwanska, coached by tennis legend Martina Navratilova, has had a smooth passage through to the fourth round, winning all three matches in straight sets.
"I think playing her is always a great challenge," said Radwanska of Williams. "I think she's still playing great tennis even though she's a bit older.
"She's still really fit and playing at a high level. It's going to be another good match."
Venus Williams leads Agnieszka Radwanska in their head-to-head 5-4, but the Pole has won their last three meetings, all in straight sets.
"She's played really well against me in the last matches," said Williams of her opponent. "I was hoping to have an all-American round of 16 with Varvara, but it didn't work out."
The players are out on court, with Venus Williams sticking with her green and white 'eye of the tiger' print dress for this last 16 encounter....