according to LFC statistics, Kewell has scored 9 times this season in league/cups/Uefa, and Owen 9. Where Kewell is 6 in league and 3 in UEFA/cups and Owen is 8 and 1.
LFC stats
So saying he is number one is stretching the truth, he is equal first for all games of the season, and second for league games.
Aside from this, ideally for LFC Kewell would be one of the highest scoring midfielders in the league beating Pires and Scholes and Owen would be beating RVN and Henry.