Tony Pulis has praised Nottingham Forest boss Aitor Karanka as he prepares to return to the Riverside Stadium.
The Spaniard enjoyed a largely successful spell at Boro, guiding the club to the Premier League in 2016, before departing a year later.
But Karanka is now back in management at the City Ground and has transformed a Nottingham Forest side keen to return to the top flight after a near-two decade absence.
In have come a number of new faces coupled with an attractive brand of attacking football, and Pulis knows they will prove a stern test as his Middlesbrough side look to continue their push towards the Championship summit.
"We're playing against a decent team, Forest are a good side with some good players," he admitted.
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"Aitor (Karanka) has changed a few things around there and brought in a few players and he'll be determined to come here and try and win the game.
"He had a wonderful spell and did fantastic for the football club and got a reception last time. I'm looking forward to having a drink with him afterwards!"
Karanka's Forest currently sit 11th in the second tier but, like Boro, have lost just once in the league this season.
Indeed, they sit just one point off the play-offs at this early stage and Pulis won't be taking too much notice of their midt-table positions and knows they will prove to be yet another tough test in the 'relentless' Championship.
"If you look at the Championship now, there's not many teams not close to the top six," he added.
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"Irrespective of what the starts have been, or what they haven't been, it's such a relentless season.
"The league will ebb and flow between now and the end of the season and people will look at it and think 'we're only a few points away from this or that'.
"We know it's going to be a tough game."
The visit of Forest is Boro's fourth outing in a fortnight at the end of a hectic schedule which has seen the side in both league and Carabao Cup action.
And Pulis has been delighted with how his side have performed of late, but knows there is one key area where they must improve.
"I was really pleased," he said of the 2-0 win over Ipswich on Tuesday evening.
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"When you think that was three games on the bounce, and three very competitive games, I thought that was very good.
"But when we get the chances, we need to improve with that and it's something we need to work on."