Image source, Getty Images

Another break here will wrap up the set for Muguruza, but her streak of winning points ends when she misses the target with a backhand.

A forehand winner, cross-court and past Muguruza's stretching arm, puts her 30-0 ahead, then a couple of loose returns from Muguruza seal a morale-boosting hold for the Kazakh.

Now the opening set is on Muguruza's racket...

"Come ONNNN!" The adrenaline is pumping through Garbine Muguruza now. Another hold to love, including a neat pick-up which leaves Yulia Putintseva flat-footed, means the defending champion is well in control now.

Fourteen points on the spin now...

After a sticky start, Garbine Muguruza is finding her groove. Yulia Putintseva is not getting the Spaniard moving as much, allowing the fourth seed to control the exchanges.

Muguruza breaks to love, meaning she has won 10 points on the bounce to lead for the first time today.

Garbine Muguruza has finally found her service game - which could be bad news for Yulia Putintseva.

The Spanish seed holds to love as she keeps her serve for the first time. Can she build on that?

Piers Newbery
BBC Sport in Paris

There's one good shot followed by one bad shot at the moment. So much inconsistency.

Russell Fuller
BBC tennis correspondent at Roland Garros

That was a great rally, but there was a lack of decisive hitting from Muguruza in the last shot she played. She let her opponent off the hook and Putintseva took advantage pretty well.

Image source, Getty Images

There are more breaks on Chatrier than a glass factory at the moment. Putintseva seems to have batteries in her trainers as she motors back and forth across the court to win a brilliant rally for 15-0, but Muguruza battles backs to claim the fourth break in five games.

Two service games for Muguruza, two breaks for Putintseva.

The Spanish fourth seed is a bit too eager in these opening stages, attacking the ball early - as she likes to - but not executing her thumping returns.

She overcooks a forehand at 30-40, gifting another break to the 27th seed.

Piers Newbery
BBC Sport in Paris

It will be fascinating to see how Muguruza holds up today. She's had a disappointing year but has stayed up in the top 10.

That's more like it! Putintseva earns an easy hold after a rocky start for both players on serve. A rhythm finder that one.

All pretty quiet on Chatrier at the moment, the Roland Garros crowd obviously still tucking into their déjeuner before hitting the court.

Piers Newbery
BBC Sport in Paris

There's uncertainty everywhere at Roland Garros particularly on the women's side with the absence of Serena Williams.

A lot of people didn't have Muguruza down as favourite to win her first-round match but the way she came through sent possibly the strongest signal we have seen on the women's side.

Strange to say that about the defending champion but it felt like a really big win.

BBC Sport

As well as following these words you can also listen to BBC Radio 5 live sports extra's commentary from Roland Garros.

Just click the 'Live coverage' tab on this page - it's only available online today because of the Champions Trophy cricket.

What's the Muguruza serve got then? Not much to start with. Not sure if it is a few nerves, or just a lack of rhythm, but two double faults help hand a break back point to Putintseva.

The Spaniard saves that with a backhand winner, but can't save a second. A long rally, forehand to forehand, ends when Putintseva goes to Muguruza's backhand and a lunging scoop from the fourth seed lands in the tramlines.

A bitty start from both women on serve.

What a start! Well, for Garbine Muguruza. Not for Yulia Putintseva.

The tall Spaniard uses her power to dominate Putintseva in the opening stages, leading 0-30 before the Kazak fights back to deuce.

Muguruza cracks a backhand winner to take advantage, then wallops a forehand winner to seal an early break.

Since winning the Roland Garros title last year, Garbine Muguruza has not reached those dizzy heights.

The Spanish world number five has only reached one semi-final since - a couple of weeks ago in Rome - but one thing we know about Muguruza is that, even if she is not in great form, she will scrap for her life.

And she is likely to need it against 27th seed Yulia Putintseva. The Kazakh, you will remember, reached the last eight at Roland Garros last year, where she gave Serena a hell of a fright before falling in three sets.

Putintseva to serve first...

Piers Newbery
BBC Sport in Paris

Spanish fans have made an annual pilgrimage to Roland Garros expecting success for over a decade now, since Rafael Nadal's first victory back in 2005. Garbine Muguruza joined the party last year with her maiden major title, and her compatriots are out in force on day six as they look for more success.

Bonjour mes amies! How are we? Ready for some more tennis? Of course you are.

A decent menu awaits today for those who have Chatrier tickets - and those who are following all the action (with the help of us) from the comfort of your desk/sofa/seat in your local coffee shop.

Here's the order of play on Roland Garros' show-court:

Garbiñe Muguruza v Yulia Putintseva

Nikoloz Basilashvili v Rafael Nadal

Diego Schwartzman v Novak Djokovic

Venus Williams v Elise Mertens

Image source, Getty Images

The women's singles draw at Roland Garros is more wide open than the jaws of a hungry hippo.

The absence of a blooming Serena Williams, an early exit for world number one Angelique Kerber, and defending champion Garbine Muguruza's patchy form means the eyes of quite a few top players have lit up...