Widnes hung on desperately for a victory which, more than any other result so far in Super League, marked their arrival as a real force at this level.
It was not pretty or spectacular, but the Super League newcomers grafted their way to a win which takes them to fourth place, above the likes of St Helens and Wigan, at least for the time being.
Second-placed Leeds, so prolific at home this season, were frustrated by Widnes throughout the first half.
A combination of good defence, spoiling tactics around the play-the-ball and Leeds' own sloppy handling kept them scoreless while Widnes gradually grew in conviction. They had a handy start with two penalties from Barry Eaton in the first four minutes, the second of them from half way after Ben Walker put the kick-off out on the full.
That was symptomatic of an error-ridden Leeds performance and their lack of precision with the ball cost them dear when Ben Walker threw one to his namesake, Shev, that fully deserved the term hospital pass. The receiving Walker was taken off with the after-effects of a tackle that arrived at the same moment.
Widnes had not come to Headingley to try to match Leeds at open, flowing rugby, but they looked more and more dangerous as the half went on. Four minutes before half-time they got the game's first try, the recently arrived substitute, David Mills, giving another hint of his rich potential by charging on to Steve Carter's pass and going through three tackles to touch down.
Eaton added his third goal and although Leeds were camped on the visitors' line for the last couple of minutes of the half they could not break through.
Widnes were under relentless pressure again after the break and eventually cracked after 52 minutes. Ryan Sheridan hoisted a kick and, when it dropped wide of the Widnes defence, Marcus St Hilaire was able to reach it and touchdown just before it ran dead.
Ben Walker was wide with the conversion, but this was the testing time for Widnes and they responded magnificently, the former Leeds centre, Adam Hughes, reaching Steve Carter's kick when the home side were guilty of ball-watching.
Leeds struck again with five minutes of normal time remaining, Keith Senior, who had otherwise endured a dreadful match, sending Andy Hay over. Walker added the goal, but that was as close as Leeds could get.
Leeds: Cummings; Calderwood, C Walker, Senior, St Hilaire; B Walker, Sheridan; W McDonald, Diskin, McDermott, Hay, Adamson, Sinfield. Substitutes used: Burrow, Poching, Vowles, Ward.
Widnes: Spruce; Demetriou, Potter, Hughes, Percival; Carter, Eaton; Relf, Cantillon, R McDonald, Farrell, McCurrie, Frame. Substitutes used: Weston, O'Neill, Richardson, Mills.
Referee: I Smith (Oldham).Reuse content