Simonsen is hanging onto his first-team place by his fingernails as manager Micky Adams openly scours the transfer market for a new goalkeeper.
The former Stoke City and Everton goalkeeper, who joined the Blades last summer as a replacement for Paddy Kenny, has been unable to stop the steady stream of goals that have pulled the Blades into the Championship relegation zone.
With 12 games of the season to play, Adams views the signing of a new goalkeeper as a priority but pulled the plug on a deal for Northern Ireland international Roy Carroll this week due to concerns over his fitness levels.
Speaking ahead of today’s trip, Simonsen said: “All the goals that go in can knock you – but I am big enough to stand up and take whatever comes my way.
“The amount of goals that have gone in is totally disappointing. Unquestionably, we should not have conceded that many – but I can’t worry about it, we just have to keep going. The next game is the one that counts, everything that has gone by is forgotten. If we can get a clean sheet at Portsmouth and three points it will be the platform we need to go forward.”
Adams dropped Simonsen for his first game in charge against Burnley on New Year’s Day but replacement Richard Wright lasted only 45 minutes before suffering a thigh injury and has not been available since.
Estonian international Mihkel Aksalu is also ruled out by a back injury so George Long, 17, is the only other goalkeeper at the club pushing for a first-team place.
The Blades have yet to win since Adams’s arrival as manager 12 games ago and are six points adrift of safety.
Simonsen said: “We need five or six wins at least now to get out of trouble but the belief is still there and we have to keep battling away. We have under-performed this season and anyone who says any different is a liar. We have got 12 games to put it right. We can’t afford to let our frustrations get the better of us.”
Five consecutive victories have lifted Portsmouth away from danger and into the play-off race.