Both sides won their opening group fixtures last month. Swansea enjoyed a memorable 3-0 win over Valencia at the Mestalla, while St Gallen saw off Kuban Krasnodar 2-0 in Switzerland.
But Saibene thinks the manner of Swansea's win in Spain means they start as favourites for this fixture, and to come top of the pile.
He said: "For us this is a huge challenge facing an established Premier League team, who are technically very good and have players well known outside the UK.
"It was a surprise for them to win in Valencia. It was a very convincing victory and it just shows the strength of the Swansea team.
"Maybe Valencia were not in great form at the time, but the result shows the high level they are playing at. They are group favourites, just about."
But St Gallen have gone 12 games unbeaten in all competitions, mainly thanks to the goalscoring exploits of striker Goran Karanovic, who has netted eight times in 13 appearances.
They also travel boosted by Basle's victory at Chelsea in the Champions League and Saibene expects his side to give a good account of themselves.
He said: "Basle have played well against English opposition before, they played very well against Tottenham in the Europa League last season.
"They are an example for us that we can achieve something here against English opponents.
"We don't want to come here and just hide, we are going to go out and give our all.
"We can take confidence, not just from our win over Kuban Krasnodar, but also from our two games against Spartak Moscow.
"When the draw was made we were not given much of a chance to get through, but we did, and that has given us confidence, and we arrive here unbeaten in 12 games."
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- Kuban Krasnodar