Celtic's eagerness to qualify for the Champions League could work in HJK Helsinki's favour when the two teams meet in the third qualifying round, according to the Finnish side's assistant coach,
However, with Anti Muurinen's side winning 7-0 against the Icelandic outfit in the first leg of their second-round qualifier, it is all but certain it will be the Finnish club who visits Glasgow.
Rantala believes the pressure on Celtic to win through might work in his side's favour
"We want to win - they have to win," he told Press Association Sport.
"Of course there is pressure on us but not like Celtic.
"It will be a disaster for Celtic if they don't win, the Champions League is huge for them so they will be anxious.
"We are huge underdogs but you never know. We have to stay positive.
"The first leg is in
"That would be a huge benefit to us but as long as we keep the tie alive.
"If we can do that then we can cause problems at home.
"Celtic have beaten good teams at home in
"We will have to defend, not because we want to, but because they will put us under a lot of pressure.
"But I think we can cause an upset in the tie if everything goes to plan and we play to our best."
Celtic's first competitive game of the season will be the first leg of its Champions League qualifier while HJK Helsinki is in second place in its league after 17 games.
Rantala, who will be at Parkhead next Tuesday night to see
"We don't have the same resources as Celtic," he said.
"There is a huge difference. Some of their best players earn nearly as much in a week than some of our players get basic in a year.
"But it's lucky that it's not all about the money.
"It might be a good thing they haven't started their season yet.
"We have played 17 games and are in the middle of our league season.
"That is something we hope can make the gap smaller.
"But they have 30 professionals and they are fit throughout the whole year.
"So it might give us a benefit but it will not be a huge factor, it will be about what happens on the park."
HJK Helsinki coach Muurinen also noted that Celtic had yet to play a competitive game.
"It is also worth remembering that the domestic season has not yet started in
Celtic met Helsinki 12 years ago in the UEFA Cup first round, with
The Hoops won the first leg 2-0 in Parkhead thanks to a
Bayern Munich defeated Borussia Dortmund 2-1 in a brilliant UEFA Champions League final at Wembley, with Bayern's Thomas Muller heavily involved.