The Arabs saw a six-match winning streak ended by a painful 4-1 Boxing Day defeat to St Mirren in Paisley.
Saints skipper Jim Goodwin had to be substituted by Buddies boss Danny Lennon before he was sent off after clattering into a string of young United players, while Conor Newton and Marc McAusland were also guilty of heavy challenges that saw them booked.
While St Mirren finished the game with a full compliment, United saw Keith Watson sent off for a crude lunge on Sean Kelly just seconds before Jason Naismith grabbed the home side's crucial third goal.
But Rankin insists it was not St Mirren's tough tackling that kept the likes of Ryan Gauld, Andrew Robertson and Stuart Armstrong quiet.
Speaking ahead of Sunday's league trip to St Johnstone, the midfielder said: "Can they young lads handle the rough stuff? Well they are used to it Monday to Friday, so I don't see any reason why they can't stand up to it in a match.
"I don't think the St Mirren defeat was caused by their physical approach. Okay they had the impetus in the first half after going in front, but we were saying to each other that a quick goal at the start of the second and we would be back in it.
"But their keeper has had some game and then the sending off for Keith and the third St Mirren goal have swung it away from us.
"We haven't been sitting tearing our hair out after that game though. We were on a good run but now it's come to an end. Now we will just move on to the St Johnstone match."
St Johnstone boss Tommy Wright did not bat an eye when Sunday's opponents Dundee United came crashing down to earth on Boxing Day with a 4-1 defeat by St Mirren in Paisley.
While Saints were losing narrowly 1-0 at home to leaders Celtic, the free-scoring Taysiders were tasting defeat for the first time in eight games in a more emphatic way.
However, asked if the result at St Mirren Park had been a surprise, the Northern Irishman said: "No. Anything can happen in this league.
"There is not a lot between the teams and I think most managers will agree with me.
"Dundee United have been good but there have been a lot of good teams this season and St Mirren scored four against us earlier this season (to win 4-3).
"Quite often it is the team who gets the first goal who go on to win the game although I know Dundee United had a player sent off."
The McDiarmid Park manager does not believe United's defeat will give his side a boost as they try to remain in the top half of the table.
"We have to go out and play," he said. "We have to look after ourselves.
"If we play to our capabilities then we can beat any team in the league and that is what we will try to do on Sunday.
"It is a Tayside derby, there will be a big crowd there and we want to get back to winning games because teams are closing in on us for a top-six place."
Wright insists his players did enough in their defeat to the Hoops to be able to take confidence into the United match.
"Celtic are the best team in the country but aside from the goal, I thought we defended well and we got better as the second half went on," he said.
"We kept the ball better and turned them which pleased me, although I was disappointed by the result.
"So there are positives we can take and it is good that we have a game a few days later.
"The beauty of the Christmas period is that there is a lot of football played and so you don't have time to reflect on the previous game."