Crespo's Al Ain take on Kewell's Yokohama F-Marinos in Saturday's first leg in Japan, with the return to be played in the United Arab Emirates two weeks later.
Crespo was part of the AC Milan side that lost to Kewell's Liverpool in the UEFA Champions League final in Istanbul in 2005.
The Argentine great scored two goals as Milan took a 3-0 half-time lead before Liverpool famously came back to draw 3-3 and win on penalties.
Crespo joked that he meets Kewell "only in great events".
"It was a very difficult night for me but it's like this," he said of the Istanbul final.
"Now we face again and it's a pleasure to meet him again after a long, long, long time.
"We face in another situation -- no more as football players but as coaches. Life keeps going and we try to reinvent it."
Al Ain are the UAE's most successful club and will be playing in the final for the fourth time, having won it in 2002 and reached the decider in 2005 and 2016.
They have got there the hard way, eliminating Cristiano Ronaldo's Saudi side Al Nassr in the quarter-final on penalties before ending Al Hilal's record streak of 34 consecutive wins in the semi-final.
Crespo said it was "normal to feel pressure" as they prepare to play at Yokohama's stadium, which seats more than 70,000 fans.
"You play in a final in a very high event, and it's normal to feel something special," he said.
"The situation is special. We need to live with this situation and live this moment."
Kewell confident
Kewell has led Yokohama to their first Champions League final only four months after taking over at the Japanese club.
He is hoping to build on the legacy left at Yokohama by fellow Australians Ange Postecoglou and Kevin Muscat.
Kewell's side had to dig deep in the knock-out rounds, beating South Korea's Ulsan Hyundai on penalties after playing most of the semi-final second leg with only 10 men.
Kewell urged his players to "feel free to go out there and express themselves" but said the two-legged format made it a "strange" challenge.
"Usually a final goes off in a one-off game, but with this case you kind of get a second chance or you get a chance to really dominate both games," he said.
"We understand that it's over two legs, we understand that it's not finished after the first 90 minutes."
Yokohama are attempting to become the fourth Japanese side to win the trophy after three-time winners Urawa Red Diamonds, Gamba Osaka and Kashima Antlers.
Kewell warned that it will not be easy against Al Ain, who he said were "a very difficult team to beat".
"I feel that they've created the same kind of journey as us, always being the underdogs as well in their group but always coming through," said Kewell.
"It's going to be a fantastic challenge for both of us but I'm really looking forward to it."
