The Red Devils climbed above rivals Manchester City into top spot on Sunday following a 2-0 win over West Bromwich Albion, coupled with the Citizens' 1-0 loss to Swansea City.
United’s squad has been hampered with a series of long-term injuries this campaign, most notably to Nemanja Vidic and Darren Fletcher who are not expected to feature again this season.
The defending Premier League champions were knocked out of both the Champions League and FA Cup early, and run the risk of exiting the Europa League after suffering a 3-2 defeat to Athletic Bilbao at Old Trafford.
Ferguson is missing a number of key players for the encounter at San Mames, but the Scot has praised the way his team have kept going in the hunt for a 20th top flight title.
"We have done really well to hang in there," said Ferguson. "That is more or less what we have done no matter what the team has been.
"For instance, with [Phil] Jones and [Chris] Smalling not available that's a door slamming in the face again.
"But we keep carrying on and it does point to a resilience in the team that is really admirable.
"They have done exceptionally well. It's an achievement in the sense of they're still banging in there in the league.
"Yes, there was the disappointment in the Champions League but we still can win this game and I think the players believe that."
