The Spanish team, who finished La Liga in third spot, fly to Austria as favorites in the third qualifying round tie, but the international striker preferred to ring the alarm bell.

"Maybe we'll have more difficult games later in the season," Morientes told Valencia's website on Monday.

"But the Salzburg tie is very crucial because it is our path to group stage."

Morientes, who recently made the move to the Mestalla from Liverpool, said that all the team players are fully focused ahead of the Salzburg game.

"Any positive result would be very good for us, but we also mustn't undervalue the return leg where it'll be very important to keep a clean sheet at home," Morientes added.

Morientes joined Valencia in the close season from Liverpool after spending 18 months with the Premiership side.