The sense of burning injustice cannot be allowed to fester for too long; for all the psychobabble spouted about the strength of a siege mentality, there are few things more self-destructive than a suspicion that even the greatest effort may be undone by outside forces. The good news for Celtic is that they have an immediate opportunity to both vent their frustration and exorcise any sense of helplessness created by Sunday’s controversial Scottish Cup semi-final loss. The bad news? Ronny Deila’s men looked like a tired team by time-up at Hampden. As hard as they may have worked at building exactly the stamina needed for this stage of the season, having to play for some 70 minutes – including extra time – with 10 men inevitably left them appearing more than a little leggy. Celtic left back Emilo Izaguirre has called on his team-mates to focus their attention on winning the league title . Izaguirre and Celtic team-mates John Guidetti, Nir Bitton and Scott Brown look dejected during semi-final loss . Celtic are currently five points ahead of Aberdeen . As they travel to Dens Park to take on an always-dangerous Dundee, Deila, John Collins and the rest of his backroom team must find a way to lift – emotionally as much as physically – players who have seen a rare and historic Treble wrested from their grasp. Emilio Izaguirre, still low but trying to raise his eyes to the remaining challenge of finishing off with a domestic Double, said: ‘Now the Treble is finished. ‘We’ll try our best to win the league now - and next season we’ll try to win the Treble. Now it’s finished, everything is finished - and we must try our best to win the league. ‘It is hard to speak about the game after Inverness have won. It’s in the past and we must now work up the mentality now to win the league. ‘It is difficult with 10 men in a semi-final. Inverness are hungry and maybe more emotional. They controlled the ball and it was hard for us against 11 men. ‘To not have a Scottish Cup final to look forward to is so hard. We want to win the Treble but now it’s over. It’s all about winning the league now. ‘I don’t like to speak about the referee. It happens in football sometimes when bad decisions and good decisions change the game but it’s finished. Inverness won 3-2 and we’ll look to Wednesday. It’s important we move on and work on winning our next game.’ In the aftermath of such a sickening loss, Celtic have no option but to move on and concentrate on beating Dundee, re-establishing their commanding eight-point lead over nominal challengers Aberdeen. What neither Deila nor his players can afford to do, though, is completely ignore some of the lessons learned in defeat by Caley Thistle. Ignoring the obvious pointer about hoping a team umpteen officials can spot a deliberate handball on the line. The way in which Celtic were exposed by Inverness in the game’s *other* crucial moment, Marley Watkins out-pacing and out-muscling Adam Matthews before beating Craig Gordon to the ball, must be of concern. Celtic striker Leigh Griffiths has a goal-bound shot blocked by the outstretched arm of Josh Meekings . Virgil van Dijk, scorer of a wonderful opener on Sunday, admitted: ‘We will look at our own performance, because we lost. ‘It (the Josh Meekings handball) should be the key moment but the penalty wasn’t given so it’s nothing to talk about right now. We lost and we’re very disappointed. ‘We gave everything. With 10 men we kept on fighting, we had enough quality to create a goal but unfortunately it wasn’t enough. ‘It’s very disappointing of course but we need to move on. On Wednesday we play Dundee away. There is a lot of disappointment. Everybody is down but we are professionals and we need to focus on Dundee. ‘That’s a big game so we need to be ready for that. But first we need to recover.’ Celtic's Virgil van Dijk has also urged his team-mates to move on from their recent defeat by Inverness .
Emilo Izaguirre has rallied his team-mates ahead of final six league games . Celtic's hopes of winning domestic Treble came to an end on Sunday . Ronny Deila's side were knocked out of the Scottish Cup semi-final . READ: Celtic write to SFA over Josh Meekings handball controversy .