Sky Bet Championship leaders Boro head for Arsenal having stunned the nation with their 2-0 fourth round victory at Manchester City and intent on serving up a repeat in north London.
However, if they are to do so, they may have to get to grips with ??42.5million Germany international Ozil, who scored a stunning opener in last weekend’s 2-1 derby defeat at Tottenham.
The pair worked together during their time at Real Madrid, where Karanka served as Jose Mourinho’s assistant, and he knows as well as anybody the havoc the midfielder can wreak if he is allowed to get into his stride.
Karanka said: “He’s a very good lad. I spent three seasons with him – he’s an amazing player and I hope on Sunday he doesn’t have his best day.
“I hope he can rest for the league they have some important games coming up! But it’s not just Ozil, it’s Cazorla too. They have a lot of [dangerous] players.”
Boro’s win at City on January 24 was not even the biggest shock of the round as League One Bradford came from 2-0 down to beat Chelsea 4-2 at Stamford Bridge the same day.
However, after the Teessiders’ Capital One Cup exploits, which saw them lose 14-13 on penalties to Liverpool after a 2-2 draw at Anfield in the third round and their heroics at the Etihad Stadium, Karanka admits they will no longer be a surprise package.
He said: “I think Liverpool could have been a surprise, Man City was a surprise, but now everybody knows Middlesbrough.
“We played very well against City – very defensive, but very good. But we are top of the table now so for them, it is not going to be a surprise. It is going to be difficult, very difficult.
“Arsenal are another Champions League team with an amazing squad. You can say that they have some players injured, but they still have a very strong squad. It’s a good challenge for us.
“We didn’t fear Liverpool or Manchester City. Anything can happen. We go there thinking we can beat them. It’s possible. But they have an amazing squad.”
Boro climbed to the top of the championship table courtesy of Tuesday night’s 2-1 victory at Blackpool as top two Bournemouth and Derby drew at the Goldsands Stadium, and promotion very much remains their focus.
Sunday’s game will represent a very different test, but at least the pitch at the Emirates Stadium will not be the issue it was at Bloomfield Road.
Karanka said: “We are going to play on one of the best pitches in the world, so it’s not an excuse. It wasn’t an excuse at Blackpool. It was impossible to play, but there’s going to be a difference at Arsenal.”
Boro will be without injured central defender Daniel Ayala, cup-tied midfielder Adam Forshaw and defender Tomas Kalas, who is ineligible under the terms of his loan agreement, but full-back George Friend is expected to be available after illness.