The Scottish champions needed an injury-time goal from Maurice Edu to beat Sporting on away goals in the last round.

And Smith is under no illusions about the size of the task his players face against the Dutch league leaders in Holland tomorrow night.

He said: "I feel that this will be a tougher game because the circumstances surrounding the clubs are different.

"PSV are certainly steadier and they are on a good run of form at the moment and are top of the league.

"Sporting Lisbon had one or two problems to overcome off the field so we would expect a far more difficult match this time around than in the previous round.

"This season, along with FC Twente, PSV have been the steadiest of the Dutch teams, looking from the outside.

"They look as though they are having a season where they are more than capable of winning the championship.

"They have a decent physical presence in their team, they play a good level of football. They like to get the ball forward in a fairly aggressive manner and overall this season they have an opportunity in front of them to be very successful."

As well as Sporting Lisbon, Rangers have also come up against Manchester United, Valencia and Bursaspor in the Champions League.

Asked if this was their toughest challenge yet this season, Smith said: "We will have a better idea after the first game.

"In the Champions League we played against a good standard of team so we will have to wait and see how the game turns out.

"You would always look at Dutch teams, especially those having a good spell at the top of the league, as being extremely tough opposition."

Smith is well aware of the importance of returning to Ibrox with an away goal and Rangers' cause has been boosted by the return of Kyle Lafferty.

The striker has been sidelined with tonsillitis but has been passed fit enough to play, although a question mark remains over Vladimir Weiss' involvement.

Smith added: "In the European games, trying to get a goal away from home has a big influence on how the games are played.

"We would hope to do that; we managed to get two in Lisbon so hopefully we can do enough in tomorrow night's game to try and get a goal here.

"To get a forward back is a big thing for us. Lafferty can play in the wider areas and through the middle and from our point of view it's important to get some players back.

"Hopefully he can get his tonsils removed at the end of the season and the course of antibiotics allows him to play on until then.

"Vladimir Weiss is slightly different, it's awkward for a footballer to have a bruised foot. It was giving him a fair bit of discomfort yesterday so I would put him in the doubtful category."