Jurgen Klopp warned that Liverpool must remain "on alert" despite putting one foot in the Champions League final with a dominant 2-0 win over Villarreal in the first leg of their semi-final tie at Anfield on Wednesday. Two goals in two minutes undid Villarreal boss Unai Emery`s defensive game plan as Pervis Estupinan deflected Jordan Henderson`s cross into his own net before Sadio Mane slotted in a second. 

The Reds remain on course for an unprecedented quadruple of Champions League, Premier League, FA Cup and League Cup. And barring a huge upset when the sides meet again in southern Spain in six days` time, Liverpool`s season will finish with a third Champions League final in five seasons in Paris on May 28. "It is 2-0 at half-time," said Liverpool boss Klopp. "You have to be completely on alert, 100 percent in the right moment and play the second half like we played the first.