The goalkeeper should make it for the game, which offers up a chance to Stuart McCall's men to put some breathing space between themselves and those around them.
With Aberdeen and Hibs enduring a weekend stalemate, there is further opportunity for Motherwell to stake their place for that second spot and extend the gap over the chasing pack to six points with a game in hand.
And given that the remainder of the SPL sides are not in business until tomorrow night, it is a chance for McCall's men to set the pace.
It has been a frustrating time for Motherwell who have had a stop-start spell this month after the winter break.
Their game on Saturday was postponed because Hearts were involved in Scottish Communities League Cup action, so tonight's match is a chance to finally get out and try to crack on.
And after going off injured in the 3-2 win over St Johnstone a week ago, Randolph is set to feature for McCall's men.
"We have a full squad to pick from," said Well No.2 Kenny Black.
"Darren trained today and we are pretty sure that he'll be fine to take his place for the game against United.
"It has been quite a long week for us because we had no Saturday game but we have stressed to the boys how important it is that we kick on from last week's win over St Johnstone.
"Like ourselves, Dundee United will probably feel that their away form has been better than their home form this season. I'm not quite sure why that it is, but you get seasons like that.
"It is something we are trying to rectify and tonight's game is another chance for us to take points that would push us on that little bit.
"Inverness have to go to St Mirren tomorrow night and I'm sure that will be a tough one for them because Danny Lennon's side will be on a high after their performance and result against Celtic on Sunday.
"So it's a chance for us to make sure that we take our chance to edge clear in second place."
And Black also believes that the decision to appoint McCall as part of the Scotland backroom staff will benefit Motherwell.
The Steelmen assistant was himself part of Craig Levein's coaching squad and, while he admits that things didn't work out the way he would have like, it has ultimately opened his eyes to different coaching and managerial methods.
If Motherwell are successful in their quest for a second season in a row of European football, then McCall's exposure to players at the very top level can only bring an experience to his club side that will aid them in their jousts on the continent.
Black said: "I loved my time with Scotland and I am just sad that it didn't pan out the way I would have liked. But I know that it definitely adds to your repertoire as a coach.
"You are working with the top players in the country and you are coming up against players who are playing at international level.
"Some of the boys were giving me a ribbing and claiming that the gaffer had nicked my job, but it was all just a bit of humour.
"I'd love to see Stuart and Mark [McGhee] and Gordon [Strachan] do well there because it will benefit the whole country – and Motherwell will certainly win out of it too."