You have to feel a little sorry for Boserup. With everything that has happened to her opponent over the last few months I am not sure there are too many fans hoping for an upset today.

The crowd are clapping both players politely, perhaps they just want to see this one go on a little longer.

A back hand on the slide flies past Boserup as Kvitova seals another game.

Image source, Getty Images

We tick over the hour mark in this match and Kvitova is sensing victory as a lucky clip of the net cord gives her 0-30.

Boserup does well to win the next point before Kvitova hits three errors in a row to allow Boserup to head back to her seat just one game behind.

That would normally be a little frustrating for Kvitova but today I don't think she'll let it worry her.

BBC Radio 5 live sports extra

This is the view from the 5 live sports extra commentary box where Russell Fuller and Simion Briggs are hard at work.

You can just about make out the far end...

Bang. That's a big ace from Kvitova. The crashes violently against the back board behind her opponent making it sound even more dramatic.

A couple more trademark serves and that's another game in the bag. If you didn't know, you'd have no idea Kvitova had been away.

Image source, Getty Images

Piers Newbery
BBC Sport in Paris

A rain delay was possibly the least predictable event on day one, looking at the weather forecast. They will play on during light rain on clay but it definitely came down hard enough to warrant a brief exit, and prompt mass shrugging and shuffling for cover in the stands. The lone cloud appears to have passed and we should be ok now.

An important hold from American Boserup.

She is still fighting in this second set but Kvitova is in control.

Not ideal having a rain delay mid service game but Boserup deals with it well.

Image source, Get

The rain has gone. The players are back on the court. Off we go again. 15-15 in the third game of the second set.

Well said Laura. Kvitova has looked very determined out there, she has been really impressive.

Without meaning to go overboard - it is amazing Kvitova is playing here remember - should she get through here, how far do you think the Czech can go in this tournament?

Let us know at #bbctennis.

Laura: Loving Kvitova's attitude on court. Not a big fan but I'll support anyone standing strong against adversity especially this week

Where has this come from?

It has been a glorious morning in Paris but the court is suddenly hit by a heavy rain shower.

The players are staying courtside, expecting it to blow over.

Break consolidated.

Boserup threatens for a while getting to 30-30 but, despite her lay-off, Kvitova is just too good at the moment.

More smart tennis from the former Wimbledon champion takes the game as she brings Boserup to the net with the drop shot and calming finishes the point with a back hand.

Image source, Getty Images

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The perfect start to the second set for Kvitova, the worst possible for Boserup.

The Czech lefty breaks to love.

If the American is to have any chance of coming back in this match, she can't give away service games like that.

Piers Newbery
BBC Sport in Paris

A huge scream from Kvitova, a good attempt at a collective roar from the rather sleepy crowd. More spectators pour in as clouds unexpectedly pass overhead.

Former champion Mary Pierce is among those already watching from the stands, while Patrick Mouratoglou - coach of Serena Williams - was an early spectator. Mouratoglou is here largely on TV duties with Williams off the tour awaiting the birth of her first child. The Frenchman insisted she is determined to return, but in the meantime there are Grand Slams to be won, and a healthy Kvitova should be a real contender - at some stage.

That was such an impressive set of tennis from Petra Kvitova.

Seven aces and 19 winners came off her racquet. Don't forget there were serious concerns she would not play again following her injury in the knife attack at her home.

She surprised us all by entering here just six months after the incident and she has comfortably taken the first set on the biggest stage of all.

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5 live sports extra

Kvitova's fierce mental concentration and bold approach has been rewarded because finding your way through matches after such a long lay-off - knowing what shot to hit and at what time - is always hard.

Image source, Getty Images

Wow. Three big serves from Kvitova set up three set points but Boserup fights back to deuce, winning the last point with a remarkable cross court backhand winner.

Another set point saved by Boserup but not this time!

Kvitova's serve gets her through. A huge shriek as the 27-year-old seals the set.

I bet that felt good.

Petra Kvitova is really looking to go after the Boserup second serve, another big hit takes us to 30-30.

Under pressure the Californian does well to hold with two good first serves.

Now Petra Kvitova will serve for the first set.

Image source, Getty Images

It is very warm out there in Paris. They're expecting temperatures over 30C later on.

There is plenty of sweat on the brow of Kvitova but she has just cruised through another service game and is now just one game away from taking this first set.

This is Julia Boserup's third appearance at a Grand Slam, her best effort coming last year at Wimbledon when she reached the third round.

Kvitova, who is two years her senior, gives her the run around with a tidy drop shot taking us to 40-30 but a forehand from Czech player clips the tape and Boserup holds.