The challenge helmed by Lionel Messi and Luis Suarez in the Barcelona forward line might be their most significant yet in Wednesday’s mouthwatering semi-final first leg at Camp Nou. If Barca do find the breakthrough, it will be a landmark moment. Four-time winners during the Champions League era, the Blaugrana are currently on 499 goals in the competition. With many more surely still to come, here are some of their very best. Rivaldo v Manchester United, 1998 United and Barca have shared many memorable Champions League tussles and, on the ground where Alex Ferguson’s side would unforgettably lift the big trophy at the end of the 1998-99 season, they remarkably played out the second of two 3-3 group-stage draws. Brazil great Rivaldo secured that scoreline for the hosts when, with Gary Neville and Jaap Stam in close attendance, he chested Sergi’s cross with his back to goal and sent an overhead kick beyond a helpless Peter Schmeichel. Ronaldinho v Chelsea, 2005 Arriving as a consolation prize after Barcelona president Joan Laporta failed to persuade David Beckham against joining Real Madrid, Ronaldinho quickly established himself as the darling of Camp Nou. An unpredictable genius, his talents were perhaps never better demonstrated…