Well's 1-1 home draw on Saturday means that the Lanarkshire men have won just one of seven home games this campaign, which came over two months ago in a 4-1 victory over Inverness Caley Thistle.
The Steelmen's next match is a daunting trip to play Terry Butcher's high-flying side, whose last defeat ironically was the game at Fir Park back on September 2.
Despite the odds of a Well win looking unlikely, McCall has urged his side not to lose hope in pursuit over fifth three points of the season.
He said: "I think what is vital for us is that we keep believing.
"The Dundee game was very frustrating for us but we showed plenty of determination to come back from the goal down and also when clearly we were just not getting a break.
"In fact looking at the last two games with both Dundee teams if that had been last season I think you could make a reasonable case for claiming we would have got a draw against United and beaten Dundee.
"Certainly we made enough chances to win both games and it is just very frustrating we only have one point to show for our efforts.
"Right now it is looking like at home we must score first to give ourselves a chance. But at the same time we know that one win in seven SPL games at Fir Park is not good enough.
"We had a dodgy spell at Christmas time last season and we showed the character to come back from it and kick-on.
"We are certainly playing better than we did during that period and the only thing we are not doing is converting the chances we are creating.
"Hopefully if we can create the same level of chances at Inverness we can make the most of them this weekend."
McCall also had words of encouragement for Estonian hitman Henrik Ojamaa who was unlucky not to net during this last two games.
The 21-year-old has now gone 20 games without a goal for Well going all the way back to April 28 last term when he bagged a brace in a 5-1 thrashing of St Johnstone at Fir Park.
McCall said: "Henrik has had no luck at all in front of goal but he is getting in great positions and he is working the opposition keeper.
"He's still a real danger to the opposition and he just needs a break."
He added:"The message I have been getting across to the lads is that we just have to keep doing what we have been doing and if we do that things will change and we will get the results we deserve."