The Portuguese star's unrest at Real Madrid is well-known, but his former manager at the Red Devils has jokingly described a return to Old Trafford as nothing more than a hope
The Portuguese forward admitted recently that he misses his former manager and described him as his "father in football".
This prompted Sir Alex to talk of his continued admiration for the Real Madrid man, but described him as "unbuyable", having scored 165 goals in 162 games for los Blancos.
With the Portuguese winger’s disquiet at the Santiago Bernabeu well-known, the Red Devils manager jokingly told reporters that bringing Ronaldo back to Old Trafford is "a Christmas wish - we have them every year!"
United currently sit second in the Premier League table after losing 1-0 to Norwich City, one point behind reigning champions Manchester City who emphatically won 5-0 against Aston Villa on Saturday.