Both players have slipped down the pecking order under Mikel Arteta, who is expected to sanction their exits either during the winter window or at the end of the season, when Tierney's contract expires.
Celtic boss Brendan Rodgers has confirmed that Tierney is likely to re-sign for the Scottish champions on a free transfer at the end of the season, although the Bhoys have not yet given up hope of striking a deal before the January deadline.
Meanwhile, Zinchenko - whose deal runs until 2026 - is believed to be on the radar of both Borussia Dortmund and Atletico Madrid, and Watts can envisage the Gunners doing business for the Ukrainian for around the £15m-£20m mark, even if that would represent a slight loss on the £29.3m the paid for him.
"Tierney, I think they'd rather just keep around until the end of the season because they're not going to get much money from him. If you let him go now, you might get a nominal fee from Celtic," Watts told Sports Mole. "I don't think you can let both go.
"I think there's a good chance that one would go and I think Zinchenko would be the one that Arsenal would ideally want to go. There is interest in him from Spain, from Germany. Dortmund are definitely interested in him.
Zinchenko "the preference" to leave Arsenal over Tierney
"Whether they actually firm up their interest to make a bid, we'll have to wait and see. But I think if they did, it would be something that Arsenal would be open to.
"If Dortmund came in and you had £20m, £15m, that's something I think they would go for for a player who's now on the fringes of things at Arsenal and is quite a high earner as well. I think he would be the preference and it wouldn't surprise me if something happens with him between the end of the window."
The 2022 signing of Zinchenko from Manchester City marked the start of Tierney's Arsenal downfall, as Arteta switched from the overlapping Scotsman to the inverting Ukrainian and has persisted with that approach even without Zinchenko in the side.
Myles Lewis-Skelly and Riccardo Calafiori are now Arteta's first two options in the left-back role, and both have also excelled coming inside and in the half-spaces since making their Gunners breakthroughs in the current campaign.
Jurrien Timber and Takehiro Tomiyasu can also fill in on the left-hand side when necessary, and between them, Tierney and Zinchenko have made just five starts across all competitions in the 2024-25 season.
While Arsenal could sanction a high-profile outgoing before the February 3 deadline, they are yet to bring in a new face this month and have recently been dealt a double blow over two of their prospective attacking targets.
Watts: 'Arteta is begging for help'
The Gunners reportedly failed with a £60m offer for Aston Villa's Ollie Watkins, who is unlikely to be allowed to leave if Jhon Duran completes an expected transfer to Al-Nassr, while Rosenborg starlet Sverre Nypan has apparently decided to stay put.
While Watts is still hopeful that a deal will be done in the coming days, he has conceded that nothing appears "imminent", adding: "It is eerily quiet. I watched Kai Havertz run himself literally into the ground against Wolves to the extent that he had to be carried off the pitch by Arsenal's coaching staff at the end.
"It just shows how much Arsenal and Kai Havertz and the forwards need some help. And Mikel's been begging for it in almost every press conference. It's not hidden in the fact that he's desperate to have another option up front to lessen the load on the players that he's got.
"But it doesn't feel like anything is imminent from conversations I've had. I keep being told that they're trying, they're working, they are active in this market. But that's the same thing I was being told a week ago, two weeks ago, and they haven't managed to get anything over the line yet.
"And now time is beginning to really, really run out. I still believe they will get something done. But I can't say for certain. The closer you get to deadline, then the harder it is to get a deal done, certainly money-wise."
Arsenal's final game before the transfer deadline sees them host none other than Premier League champions Manchester City on Sunday afternoon, just one day before the winter market closes for business.
Written by
Ben Knapton