But an ace comes at the right time for a second match point for Watson.

Match point saved, thanks to a volley at the net from McNally. Deuce.

Match point Watson after McNally nets.

Back to deuce.

A delicate drop shot is just about reached by McNally but the resulting Watson lob means the Briton saves one break point. One left. 30-40.

Another seed safely through round one. Spain's Roberto Bautista Agut, seeded 23, has seen off Germany's Peter Gojowczyk 6-3 6-2 6-3 in exactly 90 minutes.

Two break points for McNally.

Nick Mullins
BBC Sport commentator at Wimbledon

We're about to share the biggest couple of minutes in Heather Watson's tennis year so far.

Fourth seed Kevin Anderson is already a break up at the start of the third set against Pierre-Hughes Herbert... who looks like he will be focusing entirely on his doubles campaign with Andy Murray in the very near future.

Caty McNally does what she can to force Heather Watson to have to serve out the match.

Reilly Opelka is now two sets to the good against Germany’s Cedrik-Marcel Stebe on Court 7, leading 6-3 7-6 (7-4).

Stebel, the world number 518 is in the main draw for the third time but is yet to win a match... Michigan's Opelka, 21, is looking a lot like he is going to get a victory at the first time of asking.

Caty McNally had three break points in that game. She didn't take any of them. Watson now one game from round two.

And here are some quotes from Serena Williams as the 23-time Grand Slam champion talks to the BBC about motivation, motherhood and recovery.

Katie Falkingham
BBC Sport at Wimbledon

Serena Williams, a seven-time champion here at Wimbledon, has just left the practice courts after an hour.

Unlike Andy Murray, she slipped into the changing rooms almost unnoticed by the fans peering through the fences, only having to pass the waiting cameras (and me!) en route. She looked calm, composed, and ready to do battle.

She kicks off her 2019 campaign against Giulia Gatto-Monticone tomorrow.

Image source, BBC Sport

Caty McNally races into a 0-40 lead, but some solid first serving from Heather Watson then saves two of the three break points. 30-40

The action begins on Centre Court in just under half an hour's time, when 2018 men's champion Novak Djokovic takes on German Philipp Kohlschreiber.

Image source, BBC Sport

Might have to get in quickly. This match might not last too much longer.

This is now proving to be a very comfortable second set for Heather Watson. The first took 63 minutes and ended in a tie-break.

This set could be done in half the time as Watson jumps into a double-break lead. This one looks cooked.

Heather Watson seems to have corrected the serving issues that blighted her first set. Another game in the bag, another hold to 15. Halfway to the second set.