Pat Sanderson will skipper the side for the trip north and is joined in the back row by Netani Talei, who returns to his former club, and Kai Horstmann.
New Zealand international Greg Rawlinson and Craig Gillies are paired at lock and Shaun Ruwers, Chris Fortey and Matt Mullan are all given a chance to impress in the front row.
An exciting back division includes Sam Tuitupou, Dale Rasmussen and Rico Gear while Joe Carlisle is given a starting spot at fly half.
"We are looking forward to getting on the paddock at the Middlesex Sevens and Doncaster after an intensive but enjoyable pre-season phase," said Ruddock.
"Doncaster will prove a real challenge at their home ground and they will be particularly buoyed and determined to do well as former Director of Rugby Clive Griffiths will be heading up our coaching team that travels to Castle Park.
"We have selected a very strong team with the likes of Pat Sanderson, Greg Rawlinson, Craig Gillies, Dale Rasmussen and Sam Tuitupou all playing. However, there are a number of youngsters that will be seen either in the starting line-up or from the bench.
"This game provides us with the first opportunity to play under the new laws and we are very much looking forward to the challenge that they bring. This is also our first full match in with new away kit and logo on show - it's pretty exciting times all round."
Warriors v Doncaster Knights
15 Chris Pennell
14 Rico Gear
13 Dale Rasmussen
12 Sam Tuitupou
11 Charlie Fellows
10 Joe Carlisle
9 Ryan Powell
1 Matt Mullan
2 Chris Fortey
3 Shaun Ruwers
4 Greg Rawlinson
5 Craig Gillies
6 Netani Talei
7 Pat Sanderson (c)
8 Kai Horstmann
Replacements: Callum Black, Tevita Taumoepeau, Chris Horsman, Aleki Lutui, Will Bowley, Jake Abbott, Ben Jones, Matthew Jones, Greg King, Alex Grove, George Crook