Bayern Munich midfielder Javi Martinez has told ESPN FC his team will have to "fight" and give their all to go past Sevilla in the Champions League.
"Maybe people think they're not as good as Barcelona or Real Madrid but I think they are," the 29-year-old said ahead of Tuesday's first leg in Spain. "If we are not at 100 percent, they can beat us."
Sevilla's 2-1 aggregate win over Manchester United in the round of 16 has brought the danger of underestimating Vincenzo Montella's side into sharp relief.
"It's a good example [of what might happen]. I think Sevilla deserved to win both games, in Sevilla and in Manchester," Martinez added. "They scored two goals in the most difficult moments of the game [at Old Trafford]. They acted and played like a big team. That is why they are dangerous."
The Spain international credited Sevilla's three consecutive Europa League triumphs (2014, 2015, 2016) for their ability to negotiate high-pressure international matches.
"They know how to play important games, they know how to do it," he said.
Martinez, a former Athletic Bilbao player, also cautioned that the German champions had to be prepared for a noisy reception at the Ramon Sanchez Pizjuan stadium.
"They scream very loudly. When Athletic Bilbao [go there], it's always a good atmosphere. It's like a party," he said. "I think it will be the same against Bayern because they have to celebrate they are in the quarterfinals of the Champions League.
"It will be like a party but they won't give us anything. To beat them we have to fight very hard. Otherwise, we will never win in Sevilla."
Bayern coach Jupp Heynckes said later on Monday that his side go into the first leg with "the greatest respect for Sevilla."
"They've been very successful in Europe in recent seasons with a good playing system and are capable of producing high level performances," said the Bayern boss. "I said after the draw that it's an absolute top opponent, perhaps they are not talked about so much as the other teams left in the competition but they are a really strong side.
"They are a classy team who play with a lot of desire and are always aggressive too."
Heynckes also had high praise for Martinez, who is in his sixth season for Bayern after signing Athletic Bilbao in 2012 for what was then a club-record €40 million.
"I have always known how good Javi is from his time at Atletico Bilbao when Bayern signed him after my recommendation," Heynckes said. "For me, Javi is an excellent defensive midfield player, provided he is both physically fit and self-confident. If this is the case, there are not many better players around.
"He is extremely important to us -- his physical strength gives us security. I recall him turning the course of the 2013 Champions League final, he started to win challenges after 20 minutes and led the side to victory."
ESPN FC's Bayern Munich correspondent Mark Lovell contributed to this report.