The Old Trafford boss remained hopeful that his squad would deal without the pace and skills of Valencia for the bulk of the season.
"You always fear when you have a good player out of your team it is going to be a loss," Ferguson said.
"But having players like Nani, Ryan Giggs and Park Ji-sung, plus Gabriel Obertan and Bebe means we have options.
"Antonio had a great season last year. He was a great signing for us. He is a young player who has been improving all the time. It is a blow losing good players but in the context of the kind of squad we have, we should be able to cope with it."
Manchester United are already missing England midfielder Michael Carrick because of an ankle injury, although Brazilian Anderson is available again following a seven-month absence with cruciate ligament damage.
With United and Liverpool set for Old Trafford's showdown on Sunday, Ferguson is expected to name a stronger line-up after resting key players for the Champions League opening encounter with Rangers.
That match ended in a 0-0 draw, and Ferguson was criticised for leaving out in-form striker Dimitar Berbatov. The Bulgarian will definitely start against Liverpool.
Ferguson said: "Dimitar has had some terrific games for us. He is enjoying his football and he will play on Sunday."
Goalkeeper Edwin van der Sar, defenders Nemanja Vidic and Patrice Evra and Paul Scholes, who all missed Tuesday's game, are also likely to be recalled.
In Valencia's absence, more responsibility may now fall upon Portuguese winger Nani.
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