Coentrao was lined up for a move to Stamford Bridge in the summer, when Chelsea feared former boss Jose Mourinho was about to lure Ashley Cole to Real Madrid.
Cole stayed put, but Coentrao could be heading for the Barclays Premier League with Evra now in Mourinho's sights for the problem left-back position at the Bernabeu.
Red alert: Manchester United are planning a move for Benfica's Fabio Coentrao
Such is the concern within Old Trafford that Evra would find the Spanish giants hard to resist that Ferguson has already launched the hunt for a replacement.
Coentrao is prominent on the United manager's shortlist after establishing himself as Portugal's first-choice left back at just 22 and catching his eye during last summer's World Cup finals in South Africa.
Coentrao, who can also operate as a winger, was an ever-present and one of the few Portugal players to impress as they bowed out to Spain in the last 16.
There were claims in Portugal last night that contact had already been made between the clubs, though a likely £20million asking price for a player whose contract has nearly six years to run may prove a stumbling block.
With Liverpool also keeping tabs on his availability, Ferguson will continue to monitor developments as he braces himself for a possible Real approach for Evra in the summer.
Question marks: Manchester United are unsure over full-back Patrice Evra's stay at Old Trafford
Updates on Coentrao's form and valuation should be readily available, after he signed up with prominent agent Jorge Mendes, who supervised the £35m double deal that took Nani and Anderson to Old Trafford from Sporting Lisbon and Porto three-and-a-half years ago.
Although United's game at Blackpool today was called off yesterday because of a frozen pitch, Ferguson confirmed that Michael Owen will be fit to face Chelsea at Stamford Bridge in a fortnight.
The 30-year-old former England striker has not played for United since the 0-0 draw at Sunderland in early October after picking up a hamstring injury in training.
Comeback trail: Owen is two weeks away from a return, according to Ferguson
Ferguson said: 'Michael's training now and he's doing very well. I would say he's two weeks away.'
The United boss was less optimistic over midfielder Owen Hargreaves, 29, who is recovering from the hamstring injury he suffered against Wolves last month, just five minutes into his first senior start since September 2008.
'It's a bad blow for the lad and it's hard to take, given the length of time he's been out and the amount of football he's missed,' the United manager said.
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