In only his third appearance for the club, the young Scot tucked away a low cross from Marc Albrighton to give Villa the ideal start at the Gerhard Hanappi Stadium after 12 minutes.
Related ArticlesCity complete Milner signingJames Milner to join Manchester CityGo on Randy, give job to serial snogger Maradona'Maradona keen on Villa job'City violated rules in pursuit of Milner, says LernerSport on televisionBut with Villa comfortably holding their own they then conceded a soft equaliser in the 32nd minute.
From the right wing Rapid captain Steffen Hofmann delivered a piercing cross with his left foot that appeared to bounce straight in inside Guzan's right-hand post beyond his despairing dive.
However, the scoreboard inside the stadium credited Atdhe Nuhiu with the goal, if so, Hofmann's delivery getting the faintest of touches off the top of the striker's head as he jumped for the ball.
Two minutes from the interval, with Villa on the backfoot after conceding the goal, Guzan then superbly clung onto a 20-yard right -foot free-kick from Hofmann.
After Emile Heskey dragged an 18-yard shot wide, captain Nigel Reo-Coker then fired into the sidenetting before Rapid substitute Rene Gartler was left one-on-one with Guzan - only to fire at the keeper.
After Austrian and Rapid supporter Andreas Weimann had replaced Albrighton in the 80th minute, Kavlak then narrowly headed a Hofmann free-kick wide soon after.
Weimann, though, was injured moments later and had to be replaced by Isaiah Osbourne for the closing stages as Villa held out for a creditable draw.