Conversation so far:
When did Michael Owen score his first competitive, professional goal?
On 6 May 1997, Michael Owen scored on his Liverpool debut against Wimbledon at Selhurst Park.
What was Michael Owen's jersey number?
Michael Owen was handed the number 7 shirt vacated by the departure of Cristiano Ronaldo to Real Madrid.

Question: what was the name of the league he joined?
Self-contained rewrite: What was the name of the league Michael Owen joined?