MK Dons pulled off a famous victory at League 1 leaders Swansea and put themselves firmly in the driving seat for a Wembley berth in the Johnstone's Paint Trophy.

Jemal Johnson's brilliantly-struck winner on 69 minutes gave Paul Ince's side a crucial advantage going into the second leg of the southern final at stadiummk on Monday.

But it was former Swans goalkeeper Willy Gueret who was the Dons' hero, producing a string of world-class saves to frustrate his former employers on his return to the Liberty Stadium.

The result means the Dons need only a draw from the return leg in six days' time to book a place in next month's Wembley final.

But Ince's troops have now experienced first-hand the threat posed by Roberto Martinez's talented outfit, and will be well aware of how slender their advantage is.

Jemal Johnson fires the Dons into a first-leg lead at Swansea.

For while the 600 Dons fans who made the trip to south Wales will head along the M4 with smiles on their faces, things could have been oh so different had it not been for their inspired French custodian.

Dons manager Paul Ince accused his side of showing too much respect to the runaway League 1 pacesetters after the game, and as white shirts flooded forward the visitors were in danger of being overrun.

Within a minute, the evasive Febian Brandy had escaped the attentions of Sean O'Hanlon and was racing into the Dons box only to be blocked by the alert Gueret.

A mini-break from Johnson aside, the Dons were under the spell of the dictatorial Guillem Bauza, who was the latest to work Gueret as he ran onto Andy Robinson's pass.

Kevin Gallen blocks a clearance at the Liberty Stadium.

Twice more the man from Guingamp had to keep his side in the game - first from the onrushing Kristian O'Leary and then again from Brandy, brilliantly attacking the ball at the striker's feet after Bauza's shot had broke kindly his way.

While Gueret was playing out of his skin, there was a nervousness about his team-mates as Swansea bustled them out of possession and forced uncharacteristic mistakes from the Dons midfield.

Dean Lewington and Keith Andrews were both booked as the Dons showed some fight towards the end of the half but there was no doubt about it - they were fortunate to take parity into the break.

But when Ince's men took to the pitch in the second half, they started to show there was more than one league leader at the Liberty Stadium.

Dons skipper Keith Andrews holds off Guillem Bauza.

Johnson was cut down in full-flight within a couple of minutes of the break and then had appeals for a penalty waved away - the man with the orange boots feeling he was pulled down by Marcos Painter as he raced onto Kevin Gallen's pass.

The individual battles around the pitch just started to edge the Dons' way - most notably that of Lewington and the tricky Shaun MacDonald, who was no longer causing the problems he instigated in the first half.

Gueret had to be alive again to save smartly from Alan Tate as the defender met MacDonald's corner on the volley, but the Dons' time was imminent as Andrews and Alan Navarro started to win some midfield supremacy.

Johnson saw a shot blocked well by O'Leary after being set up by Andrews on 68 minutes, but when the two combined again a minute later, the Liberty Stadium was stunned.

Colin Cameron tries to put the Dons on the front foot.

Andrews stood over a free-kick halfway inside the Swansea half and when Drissa Diallo's decoy run took white shirts away, the skipper quickly fed the unmarked Johnson.

With one touch and a flash of those tangerine boots, the ball fizzed past Dorus de Vries and into the bottom corner.

Cue wild celebrations among the away supporters, who smelled an upset and yet another away victory.

But the spotlight was not off Gueret for long as the Frenchman exceeded his own magnificent standards with the pick of his saves on the night two minutes later.

Substitute Thomas Butler thought he finally had the Frenchman beaten when he cut in off the left and curled a right-foot shot towards the far corner.

But Gueret flung himself, full-length to his left and tipped it round the post to leave men in white shaking their heads.

Shaun MacDonald takes on Danny Swailes.

Navarro drove a shot just over as the visitors grew in confidence but it was Johnson who missed the best chance to provide a two-goal cushion - shooting straight at de Vries after a swashbuckling run from defender Danny Swailes down the left.

As Ince pointed out after the game, that wouldn't have settled the tie, but it would have made Swansea's task all the more difficult come Monday.

But a 1-0 win over the top-ranked team in the competition in their own backyard will do very nicely.

Get ready to light the blue-touch paper at stadiummk on Monday.

Swansea City: de Vries, Rangel, Monk (c), Tate, Painter, Anderson (MacDonald 1), Way, O'Leary, Robinson (Butler 57), Bauza (Duffy 65), Brandy.

Subs not used: Austin, Allen.

MK Dons: Gueret, Diallo, O'Hanlon, Swailes, Lewington, Dyer (Baldock 90), Andrews, Navarro, Johnson, Cameron (Stirling 65), Gallen (Carbon 90).

Subs not used: Abbey, Howell.

Goal: Johnson 69

Booked: Lewington, Andrews, Navarro

Attendance: 10,125 (576 away)

Referee: Mr A Bates