Follow live text of tie at Rugby Park
Kilmarnock will host St Mirren in quarter-finals
Dackers drills in early Killie opener but Stirton levels from tight angle
Lyons thumps hosts back in front from Mayo knockdown
FT: Kilmarnock 2-1 Dundee United
That's all for today's live coverage.
Congratulations to Kilmarnock and stay tuned for more live Scottish football action this week in the Champions League, Europa League and Conference League.
FT: Kilmarnock 2-1 Dundee United
Kilmarnock manager Stuart Kettlewell tells BBC Scotland: "When I came in on day one, if you'd offered us this start [to the season], we would have bitten your hand off.
"Coming here today, I know the challenges Dundee United have faced but they're a good side.
"We had a bit of control in the game, created one or two chances but then I felt we sunk. We gave them some sort of incentive and we were disappointed to be pegged back. I thought the players responded well and overall I felt we deserved to win based on chances created but that doesn't mean it was an easy game.
"In phases of the game, in and out of possession, we're going to have to be better. But given time, and over the course of the season, we'll continue to get better. We need to improve all the time and make sure we're not standing still."
On the St Mirren tie, Kettlewell added: "Two teams that will be relatively well matched. We have that wee added bonus of the home tie but we've got a lot of football to take care of between now and then."
Image source, SNSFT: Kilmarnock 2-1 Dundee United
Kilmarnock are one match away from the Premier Sports Cup semi-finals and a trip to Hampden.
St Mirren will provide a stiff obstacle, however.
Image source, SNS
Image source, SNSKilmarnock return to Scottish Premiership duties on Saturday, hosting Dundee.
Dundee United are not in action next weekend, with their next engagement away to Dundee on 31 August.
FT: Kilmarnock 2-1 Dundee United
Cammy Bell
Former Scotland goalkeeper on BBC Sportsound
Jim Goodwin will be really disappointed because when you look at the [second] goal it's a set piece, you can defend it better.
That was the difference. That little bit of quality from Brad Lyons sees Kilmarnock into the next round.
Image source, SNSIt's Kilmarnock who progress to face St Mirren in the Premier Sports Cup quarter-finals.
That tie at Rugby Park will take place on the weekend of 20 and 21 September.
It was an entertaining second-round tie in the East Ayrshire sunshine, with three very good goals, Marcus Dackers and Brad Lyons scoring either side of Owen Stirton's Dundee United equaliser.
United's week takes another blow after exiting the Conference League in midweek.
Image source, SNSBrad Lyons scored Kilmarnock's winner
Kilmarnock 2-1 Dundee United
Dundee United try to get some crosses into the Kilmarnock box but they cannot find a way through.
Kilmarnock 2-1 Dundee United
Four minutes of added time to be played at Rugby Park.
Kilmarnock 2-1 Dundee United
That really would've been curtains for Dundee United.
Marcus Dackers head-flicked on a long ball and Bruce Anderson was through but Yevhen Kucherenko saved superbly.
Kilmarnock 2-1 Dundee United
Further alterations for Kilmarnock with Kyle Magennis and Rory McKenzie on for Brad Lyons and David Watson for the final few minutes of regulation time.
Kilmarnock 2-1 Dundee United
Kheredine Idessane
BBC Scotland at Rugby Park
Ben Brannan got a standing ovation from the home fans as he was substituted. Another wonderful shift - nearly bent one in to the top corner for the second week running and provided the most gorgeous cross-field 70 yard pass for Killie's opener. What a prospect Kilmarnock have on their hands.
Image source, SNSKilmarnock 2-1 Dundee United
Ben Brannan's work is done for the day. He makes way for Dominic Thompson in the latest Kilmarnock change.
Kilmarnock 2-1 Dundee United
Northern Ireland international Brad Lyons made no mistake with this volley to put Kilmarnock back in front.
Image source, SNSKilmarnock 2-1 Dundee United
David Watson takes a free-kick in a shootable position but it's high and wide and Dundee United are off the hook for now.
Kilmarnock 2-1 Dundee United
More work for referee Kevin Clancy to do as Brady Lyons is pulled down by Krisztian Keresztes. It's a booking for the Dundee United defender.
Kilmarnock 2-1 Dundee United
How will Dundee United respond with around 19 minutes left?
Can Kilmarnock put this tie to bed with a third goal?
Kilmarnock 2-1 Dundee United
There were a series of substitutions just before that goal and, now there's a water break, here are the changes.
Panutche Camara and Dario Naamo are on for United in place of Amar Fatah and Craig Sibbald.
For Killie, Bruce Anderson has replaced Liam Polworth.
Brad Lyons
It's a captain's contribution from Brad Lyons as he volleys Kilmarnock in front.
The midfielder returned to the starting line-up today and took that one sweetly following Lewis Mayo's headed knock down at a free-kick.
Kilmarnock 1-1 Dundee United
It's a scorcher in East Ayrshire.
Image source, SNS
Brad Lyons scored the winning goal for Kilmarnock
Returning captain Brad Lyons netted the winner against Dundee United as Kilmarnock set up a Premier Sports Cup quarter-final at home to St Mirren.
Marcus Dackers got Killie up and running in the scorching Ayrshire sun as he latched on to Ben Brannan's perfectly-weighted long pass and smashed beyond Yevhen Kucherenko in the Dundee United goal.
Things got worse for the visitors when striker Max Watters was forced off injured after 17 minutes.
However, his replacement, 18-year-old Owen Stirton, proved his worth by slotting the equaliser just eight minutes later. Stirton took the ball from Amar Fatah before wrongfooting his marker inside the box and squeezing the ball into the far corner.
Having lost on penalties to Rapid Vienna in Conference League qualifying on Thursday, United's tired legs began to show, perhaps epitomised by Fatah slashing a shot wide under limited pressure inside the box.
Youngster Brannan had a chance to restore Kilmarnock's lead as his bending shot edged just beyond the top corner.
But Stuart Kettlewell's side found the decisive strike as Lyons volleyed the ball through Kucherenko's legs from Lewis Mayo's headed knockdown.
Kilmarnock manager Stuart Kettlewell: "When I came in on day one, if you'd offered us this start [to the season], we would have bitten your hand off.
"We had a bit of control in the game, created one or two chances but then I felt we sank. We gave them some sort of incentive and were disappointed to be pegged back. The players responded well and overall I felt we deserved to win."
Dundee United manager Jim Goodwin: "We always had a concern about this afternoon's fixture given the exploits on Thursday night.
"The boys have played 120 minutes of football on Thursday, very little time to recover for the game, Kilmarnock were the fresher team and I think that showed. But that's no excuse for some of the goals we conceded.
"The first goal was shocking, the second goal is embarrassing. We've had numerous warnings in the last couple of games, we've not dealt with a wide free-kick."
After the opportunity to rate players has closed, the score displayed represents the average from all the submissions by BBC Sport users.
Manager: Stuart Kettlewell
Formation: 3 - 5 - 2
Manager: Jim Goodwin
Formation: 3 - 4 - 3
Manager: Stuart Kettlewell
Formation: 3 - 5 - 2
Manager: Jim Goodwin
Formation: 3 - 4 - 3
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