Seth Johnson was given a breathtaking reminder of what lies in store at Leeds - only to witness a sting in the tail as ten-man Troyes handed themselves a UEFA Cup lifeline.

Watching from the directors' box, £7million signing Johnson could have been nothing but impressed with the way his new team-mates initially dismantled the French League side, with Mark Viduka and Lee Bowyer scoring two goals apiece.

The 22-year-old put pen to paper on a five-year deal during the interval to the delight of a 40,000 Elland Road crowd who had just witnessed a pulsating opening 45 minutes of this second round, first leg tie.

But striker Patrice Loko, the 26-times capped France international and a player once reputed to have suffered a mental breakdown, replied with a brace of his own to ensure the return in a fortnight remains far from a formality.

Leeds dominated the opening 30 minutes and were well worth their 2-0 lead. Viduka evaded three challenges before driving an edge-of-the-area shot beyond Heurtebis into the bottom right-hand corner for his third goal of the season in the sixth minute.

Troyes were beaten again in the 24th minute, this time Viduka setting up Bowyer for the 24-year-old to sweep home a 15-yard left-foot shot for his first goal since the opening day of the season victory at home to Southampton.

With Leeds cruising, they were then brutally exposed just after the half-hour mark as Nicolas Gousse split the defence, finding Loko and allowing the 31-year-old to round an advancing Martyn before sliding the ball into an empty net.

In the 44th minute Viduka was clearly offside in heading home a Bowyer flick from a Keane cross, although it gave Leeds a vital edge going into the break.

The fourth arrived just 47 seconds into the second half, Bowyer's persistence in chasing a long ball allowing him to feed Viduka, who was denied at point-blank range by the brave Heurtebis. But Bowyer was first to the loose ball, driving it past the stranded Heurtebis.

Just eight minutes from time Loko stole in between Rio Ferdinand and Martyn to steer home a Jermoe Rothen left-wing cross.