Pulis has had a heart-to-heart meeting with Sorensen to ensure recent events, including his error against Liverpool last week, have no bearing on tomorrow's fourth round tie at the Britannia at 1.30pm.
"Thomas has been fine," Pulis stressed.
"I've had a good chat with him and he understands the situation.
"The important thing is that we bring in competition to push everybody on, Thomas included.
"I think we are one of the few Premier League clubs to only have two goalkeepers and we need to cover ourselves with three keepers.
"Thomas would be the first to hold his hands up and say everybody needs competition.
"Elsewhere, we've got four experienced forwards and eight going for four midfield places. We've been leaving out internationals like Liam Lawrence and Glenn Whelan and they are having to grin and bear it.
"Thomas has made a couple of mistakes which get highlighted more as a goalkeeper, but he's been a fantastic signing for us.
"I will be doing my damndest to get another goalkeeper in though, whether it's David James or somebody else."
Pulis thought he would have James, pictured left, signed on loan by yesterday's noon deadline, but chief executive Tony Scholes later revealed Portsmouth could not locate one of their owners to approve the deal.
"The clubs are trying to do a deal," said Pulis. "I thought we were close last week and I thought we were close again, but it hasn't been done yet."
Pulis has vowed to field his strongest line-up tomorrow after Abdoulaye Faye and Rory Delap shook off recent calf injuries.
"Premier League football is the priority," he said, "but that doesn't mean we won't be playing our strongest team and working our socks off.
"We will play with plenty of spirit and commitment. Against Liverpool last week, people have been a little bit negative in respect of that game, which is wrong.
"We had the majority of possession and 10 corners to none. Then with the same team, they go and beat Tottenham a few days later.
"If we put in the same performance and show a little bit more quality in the final third, you never know."
Big match preview: Pages 54 & 55