The semi-final contest will be a repeat of the 2012 final in Istanbul, when six-time winners CSKA blew a 19-point lead in the second half and saw Olympiakos forward Georgios Printezis sink the game-winning shot on the buzzer.
Messina, who had joined the Los Angeles Lakers as an assistant coach after steering CSKA to a pair of Euroleague titles during his first spell in charge from 2005-2009, then replaced Lithuanian Jonas Kazlauskas in a bid to restore the Russian club's domination in Europe.
"I can only say that I am new and fresh and didn't go through the difficult night that some of my players did in that game," the Italian told the competition's official website (www.euroleague.net).
"I don't think those memories can be erased. It's part of life and they can live with it and deal with the bad memories if they are surrounded by support, but no one can really know what shadow will be on the minds of the players from last year.
"Apart from that, we need to treat this as just another game. To be in the Final Four again means that we took the right decisions and that the players we chose showed they deserved the trust of the club," he said.
Having won four Euroleague titles and reached nine finals from as many attempts, the 53-year-old from Catania will bank on his record as much as on the quality of his talent-packed roster which includes four Serbia internationals and former Toronto Raptors guard Sonny Weems.
Olympiakos will again be the dark horses but their coach Georgios Bartzokas, who succeeded Serbian Dusan Ivkovic at the helm, was confident his team could repeat last year's feat against their stronger and wealthier rivals.
"We are the outsiders again but I will try to convince my players that the same can happen as last year," he said.
"There are a lot of differences, as both CSKA and Olympiakos have new coaches and some different tactics but once again CSKA will be under big pressure because they are perhaps the best team in Europe with the biggest budget and an experienced coach."
The second contest for a berth in Sunday's final features Spanish giants Real Madrid and Barcelona, who will head into the O2 Arena in contrasting moods after taking different routes to reach the showpiece event.
Eight-times winners Real, who are seeking their first title in Europe's premier club basketball competition since 1995, enjoyed a 3-0 sweep of Maccabi Tel Aviv in their best-of-five quarter-final series, having also secured the top spot in the Spanish league ahead of the playoffs.
Barcelona, champions in 2003 and 2010, have had a topsy-turvy season and reached the Final Four only after a dramatic 3-2 defeat of Panathinaikos Athens, having fought back from a 2-1 deficit in their gruelling series marred by crowd trouble in the Greek capital.
Barca will sweat on the fitness of their towering Australia centre Nathan Jawai, who faces a race against time to recover from a foot injury, while influential American forward Pete Mickeal is out with long-term illness.
Coach Xavi Pasqual acknowledged that Barcelona's entire roster would have to carry extra weight to compensate for Mickeal's absence and will in all likelihood rely on the versatility of Croatia centre Ante Tomic, named in the Euroleague's 2012-13 first team.
"Pete is a unique player due to his own particular skills and a lot of the things we did were based on those skills, so we had to adapt and find another way to win games," said Pasqual.
"The series against Panathinaikos wore us down a lot and contrary to previous years there is less time to recover but I think we will arrive in London in good shape."
Pasqual's Real counterpart Pablo Laso, whose team warmed up for the Clasico with a 78-65 Spanish league win over Barcelona on April 28, said containing Barcelona playmaker and the Euroleague's all-time leading scorer Juan Carlos Navarro would be crucial.
"We know that Navarro is a special player, hard to guard and able to generate baskets on his own," he said.
"But if you try to cover Navarro you will be left uncovered somewhere else and players like Jawai, Tomic and (Brazil point guard Marcelinho) Huertas can damage you."
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