The Spanish coach has been linked with a potential move to the Stadium of Light in the wake of Simon Grayson’s departure.
And tonight he’s fuelled the speculation by posting a cryptic message on his personal Twitter profile.
Karanka wrote: “Next stop… *thinking emoji*”, alongside an image of himself looking at the departures boards at London’s King’s Cross station.
And his tweet has led to suggestions he’s heading to Sunderland with a view to filling the hotseat vacated by Grayson last week.
“Ha’way lad get yourself up to Sunderland!!” one fan replied.
“There’s a delayed train from King’s Cross left at 21:08 and arrives in Newcastle for 00:41am could be that one? #SAFC” another said.
One Middlesbrough supporter warned Karanka off heading to Wearside though, saying: “Don’t do it. Your reputation is at stake.”
And a Rangers fan called on him to head to Ibrox, saying: “Do not do it Aitor !!!!!!!! Please say it’s Rangers.”
Karanka is free to take charge of Sunderland having been out of work since leaving Middlesbrough in March.
The former Real Madrid assistant was sacked by Riverside chiefs when Boro looked bound for a return to the Championship.
Middlesbrough ultimately ended the 2016/17 campaign in 19th position, four points and one place above Sunderland.
The Teessiders, now managed by Garry Monk, ran out 1-0 winners when they faced the Black Cats last weekend.