This week Lam's side host Newport Gwent Dragons and Connacht have lost all three games they have played against Welsh opponents this season.
Duffy returns to make his 170th appearance for the province while Nathan White returns to the front row in the second change made by Lam, who has called on his side to reproduce their European form.
"We had a shorter week in terms of training sessions this week as we had to give the players a day off on Monday to shake off the flu virus," he said.
"We also had to plan without Craig (Ronaldson), Sean (Henry) and Frank (Murphy) who we lost to injury last week.
"With the forecasted weather conditions, back three coverage for kicks is crucial so it's great to bring back the experience and voice of Gavin Duffy.
"Dragons are an improved side this year. They're seventh in the table and it will be another tough challenge this week.
"We know that we need to put them under pressure right from the kick off. If we bring the heart, that was so evident in our Toulouse games, to our roles in the game plan it will give us a great opportunity to achieve the outcome we all want."
Newport Gwent Dragons' only victory in their last four RaboDirect PRO12 fixtures was 23-8 away at Glasgow in round eight - their only victory on the road since they beat Zebre in Parma in February.
The Welshmen have lost their last three matches against Irish opponents and have won just once away from home at an Irish Province since 2004: 16-14 over Ulster at Ravenhill in September 2008.
Each side won its respective home game when the two teams met last season, while Dragons only previous victory in ten previous visits to the Sportsground came on May 1, 2004.
Dragons' director of rugby Lyn Jones has made just one change his pack of forwards with newly signed Cory Hill making up the second row alongside skipper Andrew Coombs.
They are joined in the front five by Owen Evans, Sam Parry and international prop Francisco Chaparro.
Dan Evans retains his place as full-back and he is joined in the back three by wingers Will Harries and Hallam Amos.
Pat Leach and Ross Wardle, who moves in from the wing, both make up the centre pairing.
And Coombs is looking for a reaction after last week's European Challenge Cup defeat to Bordeaux-Begles.
"We have to keep our heads up for when we got to Connacht on Saturday and try and take the positives from the defeat to Bordeaux-Bègles because we are bigger than that," the 29-year-old told the South Wales Argus.
"They were very powerful but in the first half we gave them a platform to play with and gave them too many penalties so they could get their driving lineout working.
"We only have ourselves to blame - you can't afford to give away three yellow cards.
"It was a brave effort by us - as it always is with the Dragons - but we are more than that now."