It's time for a stretch and a big old yawn. That's better. I suppose the general conclusion from today is that Maria Sharapova will have to become more consistent if she is to challenge for the title, while a quick win for Andy Murray in searing heat was the ideal start for the Briton.

Thanks for joining us and don't forget there will be live coverage of Wednesday's action on BBC 5 live sports extra's Tennis Breakfast from about 0700 GMT. Bye for now.

Russell Fuller
BBC tennis correspondent on BBC Radio 5 live sports extra

"Low humidity and a strong, but very hot, breeze did mitigate a temperature of 42.2 Celsius, but was it wise to risk the short-term health of the stars of the show? Tuesday's winners are forecast to face 40C heat when they return to the fray on Thursday - which could transform the second week from a tennis tournament into an Ironman contest. Football and long distance running are potentially more hazardous, but perhaps a suspension of play would be advisable on the very rare occasions that tennis is played in such extreme conditions."

Piers Newbery
BBC Sport at Melbourne Park

"As the end of the day nears, the local wildlife appears to be waking up - there are some sizeable bugs flying around Rod Laver Arena and the usual bats overhead. I wouldn't have been surprised to find a lizard crawling up my leg. Sharapova finally puts away the tenacious Mattek-Sands, despite the Russian's final tally of nine double faults and a second-serve win percentage of 38%. Enough for tonight, but it won't be later in the tournament. And there's a parting gift for the exiting spectators - "Ladies and gentlemen, there is a limited tram service due to some problems with the tracks in the heat."

David Law
BBC Radio 5 live sports extra commentator

"Maria Sharapova is one of the most relentless players you'll ever see. She keeps belting the ball back at you as hard as she can."

David Law
BBC Radio 5 live sports extra commentator

"She hasn't played very much tennis recently and is a bit rusty and not confident enough to beat players easily in the way you should at this stage. I think she'll go quite far in this tournament but I can't see her winning it."

Image source, AP

A fifth ace of the match from Sharapova takes her to within two points from victory. Mattek-Sands has no fight left in her and goes long. Two match points Sharapova. The Russian aims to the wings... Mattek-Sands's return drifts beyond the baseilne. Game over.

A number of empty seats around Rod Laver with spectators calling it a day and understandably so because the clock is ticking ever closer to midnight. The match goes from 30-30 to deuce. An ace seems to move Mattek-Sands away from the danger zone, but a thunderous Sharapova backhand pins Mattek-Sands onto the baseline and the outstretched American can do little but biff a forehand into the net. There's steam coming from Sharapova's nostrils. She senses the time is right to pounce. Break point. Double fault. Sigh. Sharapova to serve out the match.

Sharapova attempting to increase the intensity by grunting and groaning as throws one flame thrower after another from the baseline. An unstoppable backhand into the corner from Sharapova. Applause from the spectators. Sharapova 40-0 up. Mattek-Sands ensures it's not a blemish-free hold but Sharapova comes up with an ace out wide and a hold to 15 will suffice.

Mattek-Sands has reduced the number of unforced errors, making merely seven so far in this set. The world number three goes long once again and the American creeps ahead for the first time in this match.

Crash! Bang! Wallop! At 30-15 Mattek-Sands is in contention, but does she believe? Oh, yes, and then some. A crisp backhand winner down the line earns Mattek-Sands two break points. Sharapova, flat footed, tamely surrenders by plonking a forehand wide.

At 30-30 Sharapova seems to have put herself in prime position to pounce, but she meekly sends a return long. On the next point, though, the Russian is at her best, hitting a clean forehand winner down the line. Mattek-Sands isn't ready to launch the flares just yet, fighting on, coming through deuce and catching Sharapova flat footed to hold with a forehand winner.

Image source, Reuters

An ace out wide for a 30-15 lead but Mattek-Sands is using every weapon at her disposal to keep Sharapova within sight. She drags the Russian to deuce - although her efforts were aided by an eighth double fault from Sharapova. The American sees a break point come and go, as has often happened in this match, and Sharapova comes through that particular test, finishing with a crisp backhand down the line.

David Law
BBC Radio 5 live sports extra commentator

"There are few players better than Sharapova than putting away easy shots. Mattek-Sands is willing herself to attack. She has to because she must play beyond her normal levels to stand a chance of winning this match. She's playing out of her skin but she's still trailing."

Listen to commentary on BBC Radio 5 live sports extra (UK only)

A fine return from Sharapova forces Mattek-Sands to direct a backhand into the tramlines, presenting her opponent with a break point. The American holds firm and correctly challenges a wayward Sharapova groundstroke which had bounced long by some distance. To deuce we go. A Sharapova forehand kisses the line for a second break point but once again Mattek-Sands holds her nerve, approaching the net before coming up with a backhand winner. But it's a double fault for a third break point ... "Come on" screams Sharapova as she shuffles across the baseline to ping a forehand into the corner.

Alistair Bruce-Ball
BBC Radio 5 live sports extra commentator

Image source, AP

"I've just come back from the marathon Gilles Simon-Daniel Brand match. It was still really sticky, but at the end Simon looked like he had been walking his dog in the park. There were big crowds out there. Some people had gone to other courts to climb up and have a look. It was more dramatic than watching this match."

Listen to commentary on BBC Radio 5 live sports extra (UK only)

Mattek-Sands confidently approaches the net but can do little when Sharapova lasers a driving forehand beyond her. Such adventure was worth a try, I suppose. Another smokin' forehand is too hot for Mattek-Sands to handle and the Russian is 30-0 to the good moments after being warned for time violation. The Russian, you sense, smouldering on the inside, attempting to find her inner zen to stop her bubbling up like a volcano. She releases her anger via a crosscourt backhand winner to clinch a comfortable hold.

Twenty unforced from Mattek-Sands's racquet during that opening set, which is too high for a player hoping to defeat the world number three. In the interest of balance, Sharapova had 13 unforced errors to her name. A delicate drop-shot helps Mattek-Sands secure the first game of the second set.

At 30-0, Sharapova skips around to her forehand and goes in search of a rip-roaring winner, but her effort drifts into the tramlines and Mattek-Sands lives on at 30-15. But Sharapova, who understandably looks as if she's playing in a steam room, goes on to collect two set points and sees off her opponent with a forehand into the corner.

The diminutive Mattek-Sands already had her back against the wall before the start of this match, having lost all five of her previous matches against Sharapova. If she were to lose this opening set, as looks likely, the odds would overwhelmingly be in the Russian's favour. The American serving confidently, though, after her initial blip and at least forces Sharapova to serve out the set.

David Law
BBC Radio 5 live sports extra commentator

Image source, AP

"Mattek-Sands walked back to her chair with the towel between her teeth such was her frustration. She had Sharapova rattled there and you don't get too many chances against her because she's a great frontrunner. That'll make Sharapova more determined now to come out fighting and race through this match."

Listen to commentary on BBC Radio 5 live sports extra (UK only)