Zamora and Johnson have scored a combined 14 goals in all competitions so far this season, with the latter hitting in hat-trick in the 6-0 hammering of west London rivals QPR last time out.
The pair will be looking to continue that impressive form, especially with a possible place in England's Euro 2012 team up for grabs following UEFA's decision to hand Wayne Rooney a three-match ban for his red card in Montenegro.
"Johnson and Zamora are as good as anything in the Premier League on their day," Pulis said.
"Zamora is a very, very good player, a very good hold-up player and he can score goals as well. Johnson is bright, clever and very quick, he's always scored goals. It's going to be a tough game for us."
Pulis admitted he was a particular admirer of Zamora, who is definitely on England manager Fabio Capello's radar after having being included in the squad for the Montenegro game.
Johnson has been out of the international picture since 2007 following a succession of injury setbacks.
"I knew Bob when he started off, at Brighton, Bristol Rovers," the Potters chief added. "I've seen Bobby come through his career and it was lovely to see him get selected the other week for England as well."
Zamora's and Johnson's goals have helped Martin Jol's side recover from a slow start to the season and they are unbeaten since August, including games against Manchester City and Chelsea.
"I don't think you should forget they finished eighth last year in the Premier League," Pulis said.
"The year before they got to a European final, a major European final, so they're no mugs.
"They've got some very good players. Last year they did the double over us, they're a good side and we and certainly won't be underestimating them.
"They were a very good side under Roy (Hodgson, who led them to the Europa League final in 2010), and they finished eighth last year under Mark (Hughes) so Martin's picked up a decent club.
"They've got a system of playing that suits their team and have got a very experienced group of players.
"They haven't changed the players very much, it's 90% the same players and it's going to be a really tough game."