3-4 point high approach one-space low pincer, tenuki

White's tenuki  

It is unexpected if White ignores Black's pincer . Black can get a good result by connecting under next.

Knight's move  

In fact by frequency in a database search, here is the most common way to play. This is Black taking an aggressive line.

Continuation  

This is the way it has gone in a number of pro games ( could be at a, also). Black has developed on both sides while White still has a weak group. The result differs from a standard joseki by the presence of the stone - which makes a large difference.

Connecting under  

It is also a pro move to connect under with . Then White immediately plays as kikashi, taking a key bulge point before Black can. After that White can play a for a light shape here; or plays tenuki again.

Charles Matthews