Barcelona will be looking to remain top of La Liga and extend its winning run in all competitions to four games when it travels to Madrid to take on Atletico on Sunday. The Catalans share top spot in the league with Real Madrid, but could find themselves three points adrift by kick off, as Los Blancos play Alaves early on Saturday morning. Barcelona booked its place in the round of 16 of the Champions League on Wednesday with a convincing 3-1 win at home over Borussia Dortmund, courtesy of goals from Luis Suarez, Lionel Messi and Antoine Griezmann. The win gave coach Ernesto Valverde some breathing room after a rocky spell during which his selection policy had come under severe scrutiny and was a much-needed injection of confidence for Griezmann, who is still finding his feet at Barcelona since arriving from Atletico Madrid in a $133-million deal in the summer. Last week, the Frenchman had openly admitted he had struggled playing alongside Suarez and Messi but insisted time would help him adapting to his new teammates. Valverde echoed his striker’s stance. “A lot is said about their connection [between Messi and Griezmann], especially when they score,” Barcelona’s coach said in…