While the Dragons marked their tournament debut with victory over Ulster, the Tigers went down to Stade Francais as the Paris club gained revenge for their 2001 Heineken Cup final defeat.
"The win over Ulster means I can promote an attitude of 'nothing to lose and everything to gain' when we go to Welford Road on Sunday," said Ruddock.
"We are really excited to be going into the Tigers' den and I guess that after losing their first game the pressure is on them - they are the ones in the must win situation.
"However, they have a lot of quality players who can galvanise a side, players like Martin Johnson and Neil Back, so we know just what they are capable of producing on the day.
"That said, we can go out, take the game to them and hopefully enjoy the occasion. It will be a huge test for us but the players have shown their professionalism and commitment by coming up with that performance against Ulster despite all the things that have been going on - both on and off the field - with us in recent times.
"It must be remembered that we are a new side still trying to integrate players so this win was ahead of schedule for us and we still have the likes of Andy Marinos to come back.
"People should not expect too much from the new Welsh structure just yet because we are all still building our sides and hopefully we will show positive signs during the Heineken Cup that that process is progressing. We have to keep our feet on the ground because we are on a learning curve."