Trainer Toby Edmonds believes apprentice Jackson Murphy can continue to play a major role as his stable chases 50 metropolitan winners for a third straight season.

Edmonds had another double on Saturday at Doomben with Houtzen and Impregnable to take him to 24 metropolitan winners for the season.

Murphy, who last week outrode his 3kg claim, continued his great run for Edmonds when Impregnable won the Class Six Plate.

Murphy has had 11 rides for Edmonds and won six, including the past four in a row.

Impregnable beat his stablemate Stanley Park by a short head after the pair had been in the leading group for most of the race.

"Jackson is a very accomplished rider who still has a two kilo claim and it is no wonder he is in constant demand," Edmonds said.

Edmonds has trained 48 winners Australia-wide this season.

Murphy leads the apprentices' metropolitan title with 14 wins.