Fire 117-2published at 60 balls
Kalea Moore has been the best of the Brave bowlers so far, she bowls a second set without a boundary.
Matthews guides a full ball into the covers but can only find a fielder in this occasion.
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Hayley Matthews defends eight off final set as Fire beat Brave by four runs
Brave 162-3: Mandhana 71* (42), Wyatt 67 (37); Griffiths 2-26
Fire 165-3: Matthews 65 (38), Elwiss 28 (20), Beaumont 26 (17)
Fire's total is the second-highest in The Hundred women's competition
Brave win toss and bowl
Southern Brave beat Trent Rockets in their opening game
Welsh Fire's match against Manchester Originals was washed out
Timothy Abraham
Kalea Moore has been the best of the Brave bowlers so far, she bowls a second set without a boundary.
Matthews guides a full ball into the covers but can only find a fielder in this occasion.
Is it time for Southern Brave to return to Chloe Tryon?
New Fire batter Sarah Bryce has been out eight times in 100 balls to left-arm spin in domestic T20s.
She only averages 9.87 against the bowling type.
Dare I say it, but is Matthews eyeing a hundred in The Hundred?
Anya Shrubsole has been fairly luckless in this match but Matthews doesn't care, she twice guides the ball behind the wicket on the off-side for two more fours.
She's now on 64 from 32.
Harris run out (Bouchier) 20 (Fire 104-2)
She's miles out!
That is superb work from Maia Bouchier on the boundary.
Her throw hits the base of the stumps and Harris is out despite the dive.
Has been Laura Harris been run out at the non-striker's end?
She brings out the dive but it might not be enough to save her.
Harris responds to that impertinent appeal by clouting another six high over long-on.
Hundred up - there were 19 runs from that seven-ball set, and Harris is on 20 from 7 balls.
An appeal for caught behind for Harris. Is it this desperation more than hope?
She doesn't appear to get particularly near a wide off-side delivery. No wicket.
Not the greatest start from Maitlan Brown, a no ball brings a free hit that Harris steers to the ropes.
A wide is then followed by Harris heaving a six into the leg-side. That was big.
Expect to see Laura Harris play some shots.
Her T20 strike-rates are 163.65 and 151.37 against pace and spin respectively in T20s.
She does only average 18 against both so her innings may be short but sweet.
Harris clouts Adams through square for four to start her innings off nicely.
Beaumont st Southby b Adams 26 (Fire 80-1)
That's the breakthrough!
Beaumont comes down the ground to Adams but she's missed the ball by some way and it's an easy stumping for Rhianna Southby.
Laura Harris is the new batter.
Matthews brings up her fifty with consecutive fours from the first two balls of Georgia Adams's set, working the ball square before a deft shot to guide the ball past wicketkeeper Rhianna Southby.
The fifty has come from 26 balls.
Michael Carberry
Ex-England batter on BBC Radio
It has not been the best start from Brave.
They will be reviewing the lengths they have bowled. They have been guilty of not bowling a line and bowling both sides of the wicket.
These two high-class batters have punished them.
Beaumont 26 (16); Matthews 43 (24)
New bowler Kalea Moore stems the tide somewhat, just the four from her set.
Beaumont tries an unconventional reverse sweep and only reaches the cover fielder. Another ball rebounds into her boot, before a heave into mid-wicket is cut off at the boundary for just two.
Thea Brookes
Former Birmingham Phoenix all-rounder on BBC Radio
That was a beautiful shot from Hayley Matthews. I am in awe watching that shot. I could watch it on repeat all day.
It doesn't feel like she's forcing it either.
Mary Taylor drags it a little short and that sits up perfectly for Matthews who crunches the ball through the covers.
Both openers then reach the boundary down the ground, both times powering the ball past a diving Mandhana at mid-off.
This is a strong start for Fire - Southern Brave desperately need to break this opening partnership.
Brave introduce Georgia Adams into the attack and Matthew carves her through backward point for a boundary.
A second four behind square follows, but this is a thick outside edge.
Tammy Beaumont is in on the action now!
She's targeting mid-on off the bowling of left-armer spinner Tyron, punching her for consecutive fours in that direction - the second just out of the reach of a leaping Maia Bouchier at mid-on - before striking a huge six that clears the ropes by a distance.
Thea Brookes
Former Birmingham Phoenix all-rounder on BBC Radio
Tammy Beaumont looks very set at the moment despite the fact she's not faced as much of the strike.
A solid opening set from Mary Taylor, just four singles from it.
Tammy Beaumont comes down the ground and tries to whip her through square but she can only find the boundary fielder.