Leicester follow Lawrence Dallaglio and company to the Madejski Stadium, targeting a win which would put them clear in third spot if Gloucester lose at Saracens this weekend.
"Leicester may have had a hiccup in the first of their games over the holiday season away at Bristol, but they reminded everybody of their true class with the win over Saracens on Monday," said Smith.
"As we experienced when we played them at the end of November, their squad has real strength in depth with quality players covering all positions."
Leicester boss Pat Howard knows his players face a huge month, with Premiership games against Irish and Sale Sharks scheduled either side of critical Heineken Cup clashes against Stade Francais and Clermont Auvergne.
"I think in the last four or five games, there has been enough to show we are making the opportunities and creating well, and teams aren't scoring many tries against us," he said.
Gloucester muscled their way into the play-off picture with a bonus point victory over Leeds on New Year's Eve, but it took them an hour to claim the extras after blitzing Tykes with three first-half tries.
"This is a hugely important game for both teams, particularly with the Six Nations just around the corner," said Gloucester number eight Adam Balding, ahead of the trip to Vicarage Road.
"Although we beat Leeds last Saturday, it was a disappointing performance in many ways and something we are desperate to put right this weekend.
"I think in the last few weeks we have become more threatening with ball in hand, and we have defended in the manner we want to. We've definitely taken steps in the right direction, but we need to get a victory on Sunday."
Elsewhere on Sunday, leaders Sale Sharks will look to avenge a November defeat against Bristol by toppling the west country club at Edgeley Park, while Sharks' main title rivals Wasps will target a third successive bonus point win when Newcastle, again minus Jonny Wilkinson, visit the Causeway Stadium.