Scotland are ahead against Wales after 45 minutes at Hampden Park thanks to a goal in first-half stoppage time from Grant Hanley.
Wales controlled possession and probed from the outset as Gareth Bale, Craig Bellamy and Aaron Ramsey exchanged neat passes in the final third.
Gordon Strachan's side were dealt a huge blow after just two minutes as Steven Fletcher was forced off early after landing heavily on his ankle.
Kenny Miller came on and had Scotland's first effort on goal, heading just over the crossbar after neat approach play from Chris Burke in a fast counter.
The visitors continued to probe before the break without managing to create any clear-cut opportunities.
Hal Robson-Kanu and Robert Snodgrass were both booked for late tackles as a feisty first 45 minutes came under increasingly heavy snow at Hampden.
In three minutes of added time Scotland made the most of a corner kick to take the lead against the run of play.
Hanley rose highest at the far post to beat Boaz Myhill with a measured effort and score his first goal for Scotland.
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