Ex-Norway international Berg, 44, spent the 2003/04 campaign, the final season of his career, with Celtic's Old Firm rivals and is looking to guide Polish title-holders Legia back to the Champions League group stage for the first time in 19 years.
"They are a step ahead of us, because they play regularly in Europe but for us it's an interesting test
I expect two close meetings," said Berg ahead of the first leg in the Polish capital.
"We have the opportunity to progress if we play to our full capabilities.
"Motivation will not be a problem and I have it in abundance with Legia.
"We will do everything we can to win this week and if I can make the Rangers fans happy with that, then of course I'd be happy too," added Berg, who won the 1999 Champions League with Manchester United.
Celtic swept aside Icelandic champions KR Reykjavik 5-0 on aggregate in the previous round but coach Ronny Deila expects a far sterner challenge against Legia, who are already two games into their domestic season.
"It's going to be a difficult match against Legia, but every opponent is difficult now," said Deila, who took over from Neil Lennon last month.
"Legia are much stronger than KR Reykjavik and it's a step up."
Midfielder Liam Henderson made his European debut in last week's 4-0 second leg win over Reykjavik and says Celtic will head to Poland full of confidence.
"We're looking forward to it and we'll see how we get on out there," the 18-year-old told the club's magazine, Celtic View.
"It will be tough, and it'll be a different atmosphere in Poland, but the manager will have a plan and we'll just stick to that and hopefully we'll get the result."
The Hoops are still over two weeks away from their Scottish Premiership opener at St Johnstone on August 13 and slid to a 1-0 defeat against second-tier German outfit St Pauli at the weekend.
However, they will be boosted by the return of Irish striker Anthony Stokes who missed the return leg against Reykjavik at Murrayfield with a hamstring strain.
The Glasgow giants will again play next Wednesday's second leg at the home of Scottish rugby in Edinburgh with Celtic's Parkhead stadium still out of commission due to the Commonwealth Games.
Zenit Saint Petersburg, Panathinaikos, Feyenoord, Lille and Besiktas are among the 13 sides joining the competition in the third qualifying phase.
Five more clubs, including Premier League side Arsenal and two-time former winners Porto, will enter in the subsequent play-off round with the victors of those 10 ties advancing to the group stage.
Source : AFP
Source: AFP