Ronnie O'Sullivan in control against Matthew Stevens

Ronnie O'Sullivan was at his magical best as he took an 11-5 lead in his World Championship semi-final against Matthew Stevens.

The three-time world champion began today's play 5-3 ahead, but Stevens began the session by winning consecutive frames to level the match.

From then on though, O'Sullivan was unstoppable as he reeled off six straight frames to take control of the last-four tie.

The Rocket made two century breaks as well as scores of 98 and 90 to demonstrate his fine form as he goes in search of a fourth Crucible crown.

The third sessions begins on Saturday morning.