Irish have yet to hit the heights of last season's thrill-a-minute performances when their expansive style underpinned a first Premiership play-off appearance.
But Smith is backing the Exiles to give Sale a real run for their money in both clubs' final game before tough Heineken Cup openers next weekend when Irish visit Toulouse and Sharks meet powerful Welsh contenders the Ospreys.
"We expect the Sharks to field a very strong line-up, so we know what is coming at us," said Smith.
"It will be a tough battle in the forwards, and if we win our share of possession then our backs will more than compete with their opposite numbers.
"Our players have a big responsibility, but we are confident they can perform."
Irish hand summer signing Seilala Mapusua a home debut in midfield alongside Riki Flutey, while flanker Jason White is the solitary survivor up front from Sale's EDF Energy Cup victory over Harlequins last weekend as rugby director Philippe Saint-Andre recalls his Premiership principals.
Wasps field arguably their strongest line-up of the season so far when lowly Newcastle visit Adams Park on Sunday.
Full-back Mark Van Gisbergen has recovered from a broken jaw to make his first start since August, with Lawrence Dallaglio and Phil Vickery featuring in a pack which sees no room for their England World Cup-winning colleague Joe Worsley.
"We have seen a lot of players in a first XV jersey in the first six weeks of the season, because competition for places has been huge," said Wasps rugby director Ian McGeechan.
"I am really pleased with the way the players have bought in to the squad approach.
"We have picked this team to go out and do certain things against Newcastle. But the competition for places means we have flexibility, and for the next few weeks we can select tactically according to the opposition we are facing."
Newcastle, without an away league win since February, could find themselves facing little more than a damage-limitation exercise - despite England midfield prospect Mathew Tait's return after knee surgery.
Falcons rugby director John Fletcher believes last week's Anglo-Welsh cup win against Magners League high-fliers Llanelli Scarlets gave the club a significant lift.
"The team has a renewed confidence after the Llanelli game," he said.
"If you put it into perspective it was a really good result against a team doing very well in the Magners League, with 12 internationals in their starting XV and another four on the bench."
Andy Farrell will be on the outside for Saracens' Vicarage Road appointment with Bath tomorrow, having failed to secure a place in their match-day 22.
"Andy still needs to be given more time to adapt to the game," said Saracens rugby director Alan Gaffney, assessing the former Great Britain rugby league captain's difficult union transition.