The Masters 1000 tournament in Florida is one title that has eluded Nadal throughout his glittering career, with four final defeats hurting the Spaniard, but this could be his year after an impressive 6-2 6-3 victory against Sock.
He made the final in 2005, 2008, 2011 and 2014 and that three-year sequence will continue if he can get past Fabio Fognini in the last four.
There was little doubt he would get past Sock as his dangerous forehand was working from the off and two breaks of serve were enough for him to take the opening set in 33 minutes.
The American is having a breakout year on the ATP Tour, though, and showcased his own stunning forehand, with some monster hitting giving him an early 2-0 lead in the second set.
Nadal fended off four break points to avoid going 3-0 down and that proved decisive as the Spaniard then reeled off five successive games to clinch the victory.
The Italian Fognini is waiting in the next round after he defeated Kei Nishikori 6-4 6-2 to become the first unseeded player in 10 years to reach the semi-finals in Miami.