This play by White is rich in unexpected variations.
Black replies at a, in which case expect White to cross-cut (with transposition to two-space low pincer variations), or at b to make a wall.
After these plays Black a is usual, but requires a good ladder. Black b is interesting but gives White plenty of scope. Black c is being played currently.
With a favourable ladder, Black can play 1, 3 and 5. White 4 is normal; now White has p or q.
In this case White 2 seems to have become joseki - there are other known continuations at 4 [1] or the x points. Up to 10 is an established sequence in recent pro play.
Black 1 here limits White's tactics, and is another contemporary play. White gets out after 8.
If Black wants a wall, Black 1 here tries to keep things simple. It is however possible for White 4 to be played at 5, leading to some dangerous variations. This line can end up with a pushing battle.
[1] See Driving Tesuji Problem 2 / Solution