Daisuke Matsuzaka is knocking on the door and it's getting louder.

The rehabbin' righthander threw six scoreless innings for Triple-A Pawtucket this afternoon at Buffalo, allowing three hits without a walk and striking out two. He threw 57 of his 86 pitches for strikes.

In two starts for the PawSox, Matsuzaka has tossed 11 scoreless innings and scattered five hits. His month-long rehab clock started on April 10, so the Sox have the option of keeping him there for a while. But they didn't invest $102 million in the guy to pitch in the International League.

At some point, either Tim Wakefield or Clay Buchholz has to exit the rotation. Either that or Terry Francona will have to figure out how six pitchers fit into five spots.