Mental toughness is a thread running through winning teams and Celtic need to get that side of the game sorted. Midfielder Ki Sung-yueng admits Celtic need to show a stronger mentality against Kilmarnock tonight to move top of the SPL. Celtic were heading for the top when they were leading 2-0 against Inverness in their most recent game (27 November), but Terry Butcher's side stunned them with two late goals. Neil Lennon's side also lost a lead in their previous encounter, when Sean Dillon's injury-time header earned Dundee United a point at Parkhead. With Rangers' trip to face Dundee United at Tannadice being postponed, Celtic will go top on goal difference if they beat Killie, who have won five of their last seven games. South Korea midfielder Ki knows they must improve their focus and take the chance to lead the table. He said: "We always get the chance to go top but we always miss the chance. We have to be mentally stronger. This is our home game and we have to win for the fans as well." Kilmarnock continued their impressive form with a 2-1 victory over Hibs on Saturday, while Celtic were frustrated as they endured a third consecutive weekend without a game. Ki said: "It's going to be an advantage for them because they have played. It is a concern that we've not played for three or four weeks. But our players have enough quality and if we do what we do normally I think we can beat them. We have been able to prepare mentally and physically. We have had enough rest so we will be full of energy. The last two games we didn't play well enough. We drew two home games, which means this break has been a benefit. We've been able to think about that we've done wrong." Neil Lennon is one of many people who have been impressed with Mixu Paatelainen's side this season. He said: "Mixu has done a very good job. He has brought in some gifted players and they play in a way that seems to suit them and it's easy on the eye, which is probably something you couldn't have thrown at Kilmarnock over the past few seasons. It's been a difficult few seasons financially for them but they seem to have turned the corner on the pitch."