Torres, who struggled for form and failed to score at the World Cup where he was recovering from knee surgery, opened the visitors' account with a delicate chip in the 18th minute.
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Liverpool coach Roy Hodgson had said that he wanted Torres to miss the game but Spain paid no attention and he was on target again in the 54th minute before being substituted. David Villa and substitute David Silva scored the other goals.
Villa, who hit the crossbar in stoppage time, took his international tally to 43 goals, one short of Raul's record, amid some confusion.
The Spanish federation's website listed his total before the match as 43 but a spokesman and Spanish media said it was one fewer.
The tiny Rheinpark stadium with its capacity of just over 6,000, enough to accommodate roughly one sixth of Liechtenstein's population, was a world away from Soccer City in Johannesburg, where Spain won the World Cup just under two months ago.
But if it felt like an anti-climax, the world champions did not show it. Andres Iniesta forced a superb save from Peter Jehle after only three minutes as they quickly got into their stride.
YAWNING GULF
There was a minor scare when Sandro Wieser floated a long free-kick over Iker Casillas' crossbar but, with Liechtenstein ranked 141st in the world and without a win in nearly three years, the gulf was far too great for any real hopes of an upset.
Torres opened the scoring in the 18th minute after Iniesta had slipped the ball through to him on the break.
He was denied by Jehle from a similar position shortly afterwards but Villa added the second in the 26th minute when he collected the ball just outside the area and, despite being surrounded by defenders, managed to turn and rifle a right-foot shot past Jehle .
Spain's intricate passing moves often resembled futsal as they weaved their way through the home defence, with Jehle coming to the rescue several times.
Jehle could do nothing, however, when substitute Cesc Fabregas slipped the ball to Torres, who fired inside his near post in the 54th minute.
David Silva added the fourth in the 62nd minute and Jehle, who plays for Swiss second division FC Vaduz, prevented further embarrassment with some more fine saves.
