More groundstroke errors from Martin Landaluce. 0-30.

He pulls a point back with a well-executed drop shot followed by a simple volley at the net, and levels the game via a wide forehand from Jacob Fearnley.

But then... you've guessed it... a double fault.

I've only just noticed that Jacob Fearnley has different coloured laces on his shoes. Pink on his right shoe, black on his left.

Anyway... he closes out a hold to 15 with an ace. He leads 2-1 in the fifth set.

Shot! Martin Landaluce traps Jacob Fearnley behind the baseline before stepping in and fizzing a down-the-line backhand winner. 15-0.

He holds to 30 to halt the Brit's run of games but his serve remains a concern, hitting double fault number 12 at 40-15.

Another advantage comes and goes for Jacob Fearnley but he gets over the line in his third deuce, firing down a timely first serve which Martin Landaluce can only just get a racquet on.

Six games in a row for Fearnley.

Image source, Getty Images

Hmmm, what was I saying? Slightly nervy moments as Jacob Fearnley is pegged back from 40-15 to deuce.

He earns advantage with a dinked drop shot but then double faults. Back to deuce we go.

Jacob Fearnley can do no wrong at the moment! He opens the deciding set with a teasing lob, much to the crowd's delight.

Back to Jacob Fearnley... he's been limbering up at the back of the court and chatting with his team while Martin Landaluce takes a comfort break.

What are we thinking? Can Fearnley maintain his momentum and win in five sets? Thumbs up for yes, thumbs down for no.

Image source, Getty Images

More from Carlos Alcaraz, on his performance and what he’s looking to improve upon: “I think the level of tennis is going to be better for sure. I’m really happy with the level that I played in my first match, my first official match in four months so I think I played really good tennis and I’m really proud of it.

"But I need more matches under the belt to get again into the rhythm of the tournament and the matches so I’m pretty sure I’m going to get better and better every day.

"I’m most proud of mentally of being able to deal with everything and with the nerves in my head. I just kept it going and I’m really proud of it.”

On returning from injury to a tournament where he is defending champion: “As I said, here in this tournament and this place and this court especially, I made my dream. First major, first time becoming world number one so every time I come here it’s really, really special.

“The warm welcome I receive every time I come here is crazy and I really appreciate it. I really feel the love from the people and once the tournament is finished, the feeling I have is I can’t wait to be back next year.”

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Carlos Alcaraz speaking on-court after his round one victory: “For me it’s been a really tough five months. As I said before the tournament, I couldn’t have decided to come back in a better tournament than here in New York because it’s a really special place for me. A special tournament for me and I tried to enjoy it as much as I can.

"I missed the crowd, the energy, the competition – I missed everything. I’m just really, really happy that I was able to compete again.”

On returning from injury: “There were some doubts in the match I’m not going to lie. I’ve been thinking about ‘am I going to last the best of five, am I going to last playing four sets, five sets? I don’t know’. So I had a little bit of doubt but I tried to forget everything and tried to enjoy and focus on the things that I had to do and improve.

“I was thinking about ‘let’s see what’s going to happen in the match’ so I’m just happy that I won in straight sets and I got another win. Physically I felt really well.”

Five consecutive games, including three breaks of serve, and by my quick maths... 20 of the past 24 points for Jacob Fearnley?

Martin Landaluce saves the first set point with an ace but double faults on the second.

A remarkable turnaround for Jacob Fearnley, recovering from 5-2 down to take the fourth set 7-5.

Strap in gang, this one's going the distance.

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Wonderful! Jacob Fearnley's forehand kisses the tramline. Two set points for the Brit!

Attacking intent from Martin Landaluce as he tries to wrestle back control of this match, rushing forward and pressuring Jacob Fearney into a netted forehand.

But then, another one of those pesky double faults. 15-all.

His next net approach is unsuccessful, unable to return a powerful pass. Eek. It's all going wrong for the Spaniard.

Make that four games in a row for Jacob Fearnley, who has the crowd firmly on his side as he holds to love.

Martin Landaluce finds himself serving to stay in the fourth set.

Well, well. Not long ago, Martin Landaluce was serving for the match at 5-2.

Now we're back on serve after a break to love for Jacob Fearnley.

Is the lucky loser going to force a decider? He's won three games in a row.

Martin Landaluce is all over Jacob Fearnley, standing on top of the baseline as he pounds deep stroke after deep stroke but with a shanked forehand, he's down 0-40.

Double fault from Martin Landaluce - 0-30. Uh oh.

Jacob Fearnley eases through a hold to 15, including a couple of aces, and marches to his chair with a bit of pep in his step.

Can Martin Landaluce serve out the match at the second time of asking?

Image source, Getty Images

Jacob Fearnley goes up 0-30 before Martin Landaluce lands a first serve nearer to the baseline than the service box... is there another twist in this match?

Double fault... 15-40.

Landaluce gets stranded at the net and is beaten by Fearnley's forehand pass. The Brit has pulled one break back!

Pat Cash
Former Wimbledon champion on BBC Radio 5 Live

Alcaraz is pumped, he's really happy about that.

That is a great return. This was a danger match but Safiullin didn't really come to play and Alcaraz - just a perfect match to come into this tournament with not too much drama. Just one bad service game and that was about it.

Safiullin will be disappointed with that performance.