Craig Mackail-Smith grabbed a stoppage-time winner as Wycombe won 3-2 at Crewe amid a frantic finish.Aston Villa youngster Harry McKirdy appeared to have earned Crewe a point with a late equaliser, but the Chairboys substitute made the most of some slack defending to poke the ball home.Veteran striker Chris Porter's early penalty was cancelled out by Paris Cowan-Hall and substitute Nathan Tyson forced home from close range after which Crewe boss Dave Artell was sent to the stands for protesting.The high-flying Chairboys got off to the worst possible start when Nathan McGinley was adjudged to have tripped Charlie Kirk and Porter beat keeper Scott Brown with the sixth minute spot kick.Gareth Ainsworth's side rallied and Luke O'Nien wasted a good chance when keeper Ben Garratt parried the ball to his feet, but the midfielder lifted his effort over.Some sustained Crewe pressure ended with Eddie Nolan's thumping header flying a yard wide of the Chairboys' goal.But the struggling Railwaymen looked resolute in defence with Michael Raynes in excellent form until Adebayo Akinfenwa headed on Joe Jacobsen's free kick and Cowan-Hall rifled a half-volley into the far corner with an hour gone.Then Akinfenwa played a decisive presence in the box again, setting up Tyson for Wycombe's second from close range with eight minutes to go.Crewe substitute McKirdy drove in the rebound after Ryan Wintle's shot was parried by Brown with two minutes remaining, but Mackail Smith poked home deep in stoppage time.