Aitor Karanka is looking for the signing that is going to guarantee their promotion to the Premier League.
The Yorkshire Evening Post reports that Aitor Karanka has earmarked Fulham forward Ross McCormack as his number one priority, but they are also keeping a keen eye on Gayle, as well as Blackburn striker Jordan Rhodes.
And with Sky Sports adding that Palace expect to make a profit on the £6m they spent on bringing him to the club in 2013, it seems likely that Boro would have to part with a considerable fee to pull off a move, should pursuing their other targets end without success.
Although Gayle is yet to score in the Premier League this season, he has been useful in front of goal during his time with Palace. His record of 12 league goals in 55 games may not seem impressive, but it must be noted that he has started just 23 times.
And with a potential run in the Boro side ahead if he was to join, he may be the addition that sees Karanka's men capitalise on their current two point lead at the top of the Championship, to secure a place in the top flight.