Suler will line up against the Scottish champions in Slovenia this evening, but he was at Legia last year, the side that this week lost their Court of Arbitration for Sport appeal to be reinstated into the Champions League.
And the 31-year-old Slovenian internationalist admits he has had plenty of encouragement from his former colleagues in Poland.
"I still keep in touch with most of my team mates in Legia so you can imagine I've been asking them a lot about Celtic," he said.
"After what happened to them, they have are all very hopeful we will go and beat them. But you must remember, Celtic's two games against Legia were not true indications of their level. The game in Poland was practically Celtic's first game of the season and they had a player sent off.
"And since those games, they have changed their squad dramatically with the introduction of several new signings. Celtic are a good team who are worthy favourites."
But he revealed that Maribor do have one trick up their sleeve. "Our assistant manager Sasa Gajser has watched them in Scotland for the past week," Suler said. "He is famous as an excellent analyst of a game. He will tell us what to expect and that can give us an advantage."
Suler's former team-mates at Legia were happy to admit that they would be backing Maribor this evening. Miroslav Radovic insisted he was desperate for a rematch - this time in Europe's second-tier competition. "I'd love to play Celtic again in the Europa League," Radovic said. "I'm supporting Maribor with all my heart. So much is said about fair play, but we've not seen any decent behaviour at all from the Scots. They didn't act with class. But that's not at all surprising when there is huge cash at stake.
"We beat Celtic 6-1 fair and square.But what really p****s me off is that the people in Glasgow refused to answer their phones or respond to emails after the scandal came to light. It was a disgrace."