Well that's unexpected!

Murray casually hits an underarm serve and Duckworth scrambles to return. He manages it but his position is compromised and Murray is able to put a volley beyond the Australian.

I had to quickly whizz back iPlayer to make sure I had seen what I thought I'd seen.

Everything about Murray's play has improved considerably since the first set - he's serving better and hitting the ball cleanly and the momentum is firmly with him as he gets the early break in this third set.

A fine drop shot gives him the break point and then an error by Duckworth gives Murray the game.

Alan Jewell
BBC Sport at Wimbledon

Angelique Kerber, the 2018 champion and seeded 15th here, is into the second round having resisted a Kristina Mladenovic comeback on Court One.

Kerber led 6-0 2-0 but the world number 33 fought back and was 5-4 up in the second set.

However, the German broke in the 11th game and a backhand winner sealed her progress, 6-0 7-5.

Andrew Cotter
Tennis commentator on BBC TV

Murray has found his serve, he's found his rhythm on it, and it is making things a whole lot easier.

When Murray is serving well he bounces with a swing in his step.

Signs of tiredness creeping into Duckworth's play? He's in danger of an early break in this set as Murray has two break points but the Australian is able to pull it back with some strong serves and holds.

Kim Clijsters
Four-time Grand Slam champion on BBC Radio 5 Live

There is a different feel to Andy Murray compared to the first set. I think he knows it's crunch time and he's realised 'okay I have to stick with it and not give too many unforced errors away'.

Jonathan Jurejko
BBC Sport at Wimbledon

Better serving was a key for Murray in winning that set and levelling the match.

He improved his first-serve percentage considerably and won 15 out of 15 points when he landed them.

Duckworth only won two points on the Murray serve as a result.

And, crucially, pressure kept coming back quickly onto his own service games.

Not ideal when you're playing Andy Murray at Centre Court, especially not after your own injury issues and lack of matches.

Image source, Getty Images

John McEnroe
Three-time Wimbledon singles champion on BBC TV

First step [to improve] would be would be Murray's serve. It is key on this surface.

His attitude and belief when the going gets tough. It's not going to get any easier.

He has a pretty tough looking draw, just to get to the semis.

This one didn't quite go to plan for Alejandro Davidovich Fokina earlier, but we like the effort.

Andrew Cotter
Tennis commentator on BBC TV

You get the impression that Murray is warming to the task, and you wonder how much James Duckworth has. He just faded a little bit, although Murray did up his game.

And it is routine stuff for Murray as he takes the game and the set. Murray has muttered to himself in frustration at times in this match but he looked much happier with how things went in the last couple of games.

Duckworth hangs on in there as the Australian holds on serve. There were some confidence-boosting shots in there with a delightful lob and a drop volley that has Murray scampering.

Murray to serve for the set.

Sukh Pabial: The emotional ride that comes with watching any Andy Murray match.

We know.

John McEnroe
Three-time Wimbledon singles champion on BBC TV

Murray has been in 11 Grand Slam finals for a reason. A good shift of the game plan by Murray but you wonder why he doesn't do that more often.

Scott Pugh: Got a metal hip and still running about. Fair play

There's a change of racket for Duckworth as he looks to respond to losing the last game but it fails to halt Murray's momentum and the two-time Wimbledon champion is a game away from taking the second set.

Eighteen unforced errors by Duckworth to Murray's eight and that's where it has been costly for the Australian in this set.

Murray isn't the only Brit in action currently.

Jay Clarke - ranked 156th in the world - has just lost a first-set tie-break to American qualifier Chris Harrison on Court 18.

Andrew Cotter
Tennis commentator on BBC TV

You can see the effort on the face of James Duckworth. Draining for both men.

The pattern of this set looks like it is going to continue as Duckworth quickly finds himself 40-15 but a couple of good shots by Murray gets him to deuce and the crowd going. First he draws Duckworth up to the net with a low one-handed slice before then hitting a cross-court winner.

Centre Court roars as Murray then moves onto break point and then the decibels increase as a lengthy rally ends with Duckworth hitting his return wide. Murray has the break.