It was thought earlier in the week that they had all but signed Riley McGree, the Australian international from Charlotte FC in MLS.
The deal was understood to be worth £2million and would see the player link up with Ange Postecoglou once more with the Celtic boss knowing the player well from his time as Australia boss.
However, English Championship side Middlesbrough gazumped Celtic with an offer which could be worth £5million.
According to the Daily Record, Boro offered £2.5million upfront with a further £2.5million in add-ons.
The deal was lucrative to McGree as well with a significant contract offer.
It will see Celtic turn their attention elsewhere even with the addition of Japanese trio Reo Hatate, Daizen Maeda and Yosuke Ideguchi at the start of the window.
The club have been strongly linked with Iranian ace Mehdi Ghayedi, who moved to Shabab Al Ahli’s Ghayedi in the United Arab Emirates last year. He is one of the most highly thought of youngsters currently playing in Asia.
There has also been speculation surrounding Algerian international Ahmed Kendouci.
Kenouci is a key player for Entente de Setif and is valued at £1million. His club are not keen to sell, however, as they currently sit just two points off the top in the Algerian Ligue 1.
In addition, there have been links to AZ Alkmaar winger Albert Gudmundsson.
The 29-time Icelandic international is out of contract this summer and has reportedly told his club he has no intention of signing a new deal.