Former Rangers and Liverpool defender Vignal yesterday signed a deal at United until January, having become a free agent after leaving Atromitos in Greece two years ago.
Frenchman Vignal has been training with his new team-mates although won’t be ready in time to face Ross County tomorrow night as the SPL swings back into action.
But Houston is sure the 31-year-old full-back can make a big impact on Tayside especially after hearing what ex-Ibrox midfielder Adam had to say about the former Montpellier man.
Houston said: “We have agreed a short-term deal with Gregory until he improves his fitness. I won’t be looking for him to step up to the mark straight away because he’s not played for a while. But he’s an experienced player and I have had very positive feedback about him.
“I asked Charlie Adam about him last week and he was very complimentary about him.
“He’s got great experience and played at a very high level with Liverpool, Kaiserslautern, Portsmouth and Rangers.
“We’re a very young team so someone like that will be a valuable addition. He’s only 31 so still has plenty to offer. It’s a short-term deal but if he does well then we’ll extend it.”
Scotland under-21 pair Johnny Russell and Stuart Armstrong returned to Tannadice yesterday after facing Austria on Monday.
United face SPL new boys County tomorrow night and Houston admitted he has two mystery injury worries ahead of the Staggies visit.
He said: “Johnny Russell and Stuart Armstrong have come back from the under-21s okay which is always good.
“But we have one or two other injuries and have a couple struggling for Friday night but I don’t want to say who they are.”