AITOR KARANKA has called for his players to remain focused on the task at hand amid fears that Middlesbrough are ‘over-confident’ ahead of Tuesday night’s Capital One Cup quarter-final.

Premier League side Everton head for the Riverside Stadium wary of the threat posed by the opposition after Boro’s impressive victory over Manchester United in the previous round.

Toffees boss Robert Martinez, a friend and compatriot of Karanka, is always well aware of the way Middlesbrough defeated Manchester City in the FA Cup last season as well as forcing Liverpool to penalties in the League Cup earlier in the campaign.

But the Middlesbrough boss is afraid his own players are going in to the visit of Everton with a different mentality to what he has been used to.

Karanka said: “That would be our biggest mistake, to think that because we beat Manchester City and Manchester United and we played very well against Liverpool and Arsenal that the game tomorrow will be easy.

“If we had a really good performance against those teams it was because we were working for more than 90 minutes, fighting and working a lot.

“The atmosphere, we are close to the top of the table and we beat Manchester United in the last round and we play at home against Everton and I am feeling the atmosphere of a little bit of over-confidence and that would be a big mistake.

“Over-confidence, because I can feel the atmosphere in the changing room, the crowd, everybody is really excited and I understand that but we have to recognise Everton is a really good team and we can't just think that because we beat Manchester United in the last round or we beat Man City last season that we will beat Everton. To beat Everton we have to play at 150 per cent for 90 or 120 minutes because they are a really, really good team.”

Middlesbrough have skipper Grant Leadbitter available again after suspension and have reported no fresh injury problems, so Karanka must weigh up who is in the best frame of mind to face Everton.

Middlesbrough also travel to Ipswich on Friday, which will be their third game inside six days so Karanka will consider fatigue when he names his team to face Everton. He is determined to reach the semi-final, even if promotion remains this season’s main goal.

He said: “It is a competition the club won 11 years ago and I know how important it is for everybody but, again, we are playing against Everton and it's true if we beat them we are in the semi-finals, but we have to keep calm, we have to keep our feet on the floor because we are playing a really good team.”

“Tomorrow the cup is the priority. After tomorrow of course I will think about the game against Ipswich but today and tomorrow my aim is to prepare for the game against Everton.

“In Spain it is different. Here it was a surprise to me that the bookings in the cup count with those in the league but in Spain they don't. We have played three more games than other teams in the Championship so you can get more bookings and it's difficult.

“But we have to manage, we have to manage the atmosphere, we have to manage the motivation because sometimes you have to use substitutions to rest some players, you have to use substitutions to motivate other players because we have 20 players and have all of them motivated and fit for tomorrow.”

There will be a packed Riverside for the visit of Everton and Martinez is also keen to lead his side to glory, knowing that the Merseyside club have never won the competition Boro won in 2004.