Should Sevilla go through to the knockout stage, it will mean they won't be able to defend the Europa League title which they have won for the last three seasons.
Sampaoli has already brought a breath of fresh air to La Liga, where his side have climbed into third place and beaten Atletico Madrid along the way.
Saturday's 3-2 win at Deportivo La Coruna, where they scored twice in the last five minutes, was fairly typical of their style which is not for the faint-hearted
The shaven-headed Argentine, noted for his exuberant celebrations, turned Chile into one of the most entertaining teams at the World Cup two years ago and made history last year when he led them to their first Copa America title.
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Sampaoli likes his team to play with a fast and furious style, sweeping forward in relentless waves with seven or eight players joining the attack.
Defending has sometimes been an afterthought, although he has given Sevilla some added steel at the back and they have yet to concede a goal in the group.
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Juve's Allegri also likes his team to dominate possession but he is averse to risk-taking and often talks of the importance of "administering the match".
He admonished his side after this month's 1-1 draw at home to Olympique Lyonnais for chasing the game in the last few minutes and leaving themselves dangerously exposed. "We could have thrown our qualification down the drain," he said.
Unlike Sampaoli, Allegri is established in European football having won a Serie A title with AC Milan and two at Juventus, who he led to the Champions League final two seasons ago.
Sampaoli could claim to be the moral victor after a 0-0 draw in Turin in the teams' opening group meeting in September. This time, the onus will be on Spaniards, as Allegri has pointed out.
Juve meet Dinamo Zagreb, who are without a point, in their final group game and can bank on getting the win they will still need if they lose on Tuesday. Sevilla, on the other hand, face a much tougher final game at Lyon.
“I believe that the match (on Tuesday) is more important for Sevilla than for ourselves," said Allegri. "If we don’t beat Dinamo Zagreb at home in our final group game, then we don’t deserve to be in the Champions League."
(Writing by Brian Homewood; editing by Ken Ferris)
