HITC Sport understands Middlesbrough have two bids for defender rejected.
Middlesbrough have seen two bids for Ingolstadt defender Marcel Tisserand rejected, HITC Sport understands from sources close to the club.
Boro boss Garry Monk is looking to strengthen his central defensive options with Ben Gibson, Daniel Ayala and Dael Fry as the only recognised senior men to cover that position, while Gibson's future remains the subject of conjecture amid speculation linking him with several Premier League clubs.
Tisserand is expected to leave Ingolstadt this summer following their relegation from the Bundesliga.
The 24-year-old impressed for Ingolstadt despite their relegation and a number of clubs across Europe have been monitoring his situation.
A number of Premier League clubs have shown an interest in Tisserand, but Middlesbrough are hoping to lure the DR Congo international to the Riverside.
Boro chief Monk is looking to build a side capable of winning promotion back to the Premier League at the first time of asking and Tisserand's pace and versatility, in that he can play at centre-back and right-back, would make him a valuable addition to his plans.
However, Ingolstadt have so far rebuffed Middlesbrough's first two offers for Tisserand with the defender now training away from the rest of the first-team squad at the German club as Ingolstadt wait for their valuation to be met.
It remains to be seen if Middlesbrough will come back with a third offer for Tisserand before the close of the transfer window with Ingolstadt digging their heels in over the defender.