Janssen faced Wouter Vaes in his preliminary round clash and breezed past Vaes to take his place in the main draw.
The Belgian was making his debut but made light work of his opponent hitting an 82 average.
Sherrock is through to the second round after seeing off Corrine Hammond in a repeat of last year’s first round.
She hit three 15 dart legs with an average just short of 90. This was with a best of a 108 finish and two maximums.
The Milton Keynes ace only allowed Hammond one leg throughout the match and will be one of the favourites now Ashton has gone out.
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Roger Janssen (82.44) 3-0 (78.69) Wouter Vaes Fallon Sherrock (89.67) 2-0 (81.24) Corrine Hammond 20:45 – Mark McGrath Vs Adam Smith-Neale 22:00 – Wayne Warren Vs Mark Layton