Roelof van der Merwe has his head in his hands as Gareth Berg goes down on one knee for an attempted slog, misses, and sees the ball just miss his off stump.

Just two from the over, though.

Jamie Overton has switched to the Nursery End after two overs from the Pavilion End and he concedes just three.

Roelof van der Merwe has been given the Pavilion End, where the short boundary is on the off side for the right-handers.

Rilee Rossouw looked in superb nick for Hampshire - no wonder Somerset were delighted to see the back of him.

Roelof van der Merwe took 3-29 in the semi-final victory against Nottinghamshire and the slow left-armer is into the attack now for Somerset.

Hampshire take three singles and a two from his first over.

Ged Scott
BBC Sport at Lord's

"There’s probably no exact cricketing science formula to judge these things, other than maybe to pop upstairs to one of the commentary boxes and check the sound levels.

"But generally, the importance of a batsman’s wicket can be assessed by the roar from the fielding side’s fans when their man claims his scalp.

"In which case, after his match winning century here last year, Rilee Rossouw’s dismissal with that classic Harrow drive must have been very important!"

Sam Northeast takes a single into the leg side to bring up the Hampshire 100 but that is a good over from Lewis Gregory. Just one run came from it.

An expensive over from Jamie Overton but, crucially, one that brought the huge wicket of Rilee Rossouw.

Gareth Berg has come to the crease to join Sam Northeast, who looks like the key man for his side now.

Shaun Udal
Former England and Hampshire spinner on BBC 5 Live Sports Extra

"You'd have to describe that as hammer blow. It was an innocuous delivery with a bit of width. Hampshire have got to rebuild now and look to bat the 50."

Hampshire certainly didn't make the start they wanted at Lord's after choosing to bat first. Here's how they lost their third wicket.

Rilee Rossouw is timing it superbly and he drives Lewis Gregory through mid-on for four. His arrival has allowed Hampshire to up the scoring rate without taking too many risks.

Jamie Overton, who has been playing for Northamptonshire on loan in the County Championship, is back with Somerset for white-ball duty and into the attack in place of Josh Davey, who has two overs up his sleeve for later in the innings.

He is unfortunate when Sam Northeast goes for an expansive drive and gets an inside edge that misses the stumps and finds the fine leg boundary.

Overton's opening over costs seven runs.

A beautiful drive through mid-on brings captain Sam Northeast his second boundary as Hampshire try to counter-attack.

Five come from that Lewis Gregory over.

Somerset captain Tom Abell keeps Josh Davey going with an eighth over in this spell and the new-ball bowler maintains his excellent figures, although Rilee Rossow pounces on the final delivery of the over and pulls it to the boundary.

Rossouw opened in last year's final against Kent and made 125 off 114 balls. Somerset have been warned.

Image source, Rex Features

Vic Marks
Ex-England spinner on BBC 5 Live Sports Extra

"He's looked in terrific form, Rossouw, since he's come in. They weren't the worst balls, the ones that were driven, but he just went through the line, and the pull shot was pretty impressive too"

Three boundaries in the overs. Rilee Rossouw is not a man to hang around and he starts Lewis Gregory's third over with a push through extra cover for four followed by a big hook that also finds the fence.

After a dot ball, Roussow gets four more with a drive through mid-off.

Five dot balls followed by a boundary through the covers and up the Lord's slope from Sam Northeast.

Josh Davey has 2-21 from his seven overs.

Another excellent over from Somerset, this time from Lewis Gregory, leaves Hampshire with a rebuilding job to do.

Josh Davey is into his sixth over, and aside from a couple of stifled lbw appeals it's a quiet one.

Sam Northeast claims a single but Davey is giving the batsmen nothing and he beats Joe Weatherley's inside edge with a beauty from the final ball of the over.