Celtic are working to get two further deals over the line before the transfer window closes in Scotland at midnight.
Neil Lennon has already snapped up Greg Taylor from Kilmarnock in an effort to add to his defensive resources and now the Bhoys are working on further deals.
Manchester United defender Lee O'Connor and Manchester City's Jeremie Frimpong, also a defender, are the players Celtic are trying to get in through the door, according to STV.
O'Connor, a Republic of Ireland Under-21 international, is down the pecking order at Manchester United and has been restricted to Under-23 game time.
Celtic are aiming to take the 19-year-old north of the border this summer.
They also want to raid Manchester United's local rivals Manchester City to bring in a further defender before the window shuts.
Promising Dutch defender Frimpong is the man Celtic want to sign and they are working to do so.
Frimpong has also been playing Under-23s football in the Premier League 2 and is able to operate at right-back or left-back.
He has been capped by the Netherlands up to Under-19 level.
