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Former world player of the year Messi, 27, has inspired Argentina in Brazil.
The Barcelona forward has scored in all three games and is one goal shy of Maradona's 1986 five-goal haul, but Mehmedi says it is not all about Messi.
"With all due respect for his qualities and class, I think too much is talked about just Messi," said Mehmedi, 23.
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"He is exceptional, no question, but that is not all, he has very good players around him. We will not neglect the preparation nor in the game itself," the Freiburg striker said ahead of their last-16 clash.
Argentina are unbeaten in their six previous games against Switzerland but Mehmedi says his side are not heading into the game at Corinthians Arena just to make up the numbers against one of the pre-tournament favourites.
"Swap jerseys with Messi? I'm not here as a tourist," he said. "Switzerland is in the second round of a World Cup."
Mehmedi knows if his side can defeat Argentina in Sao Paulo they will cause one of the biggest shocks of the 2014 tournament in Brazil.
"I know the quality and potential of this team," he continued.
"If we defeat Argentina, we write a piece of World Cup history and many people in Switzerland will be proud of the team.
"I even think such success would see the world take notice, but we are not naive.
"It will take an absolutely top performance of each one of us. And I assure you, everyone will do everything we can to provide these and tearing for Switzerland."

A point against the Dutch side could keep Celtic in the hunt if Group A rivals Fenerbahce fail to beat Molde in Norway, but Deila feels his team must keep their fate in their own hands.
"I still see an opportunity to go through, and that's what we are going to fight for," Deila said.
"We have to go for winning the game."
Group winners Molde registered home and away victories over Celtic to leave the Scottish champions bottom of Group A with two points from their four matches.
Ajax are only a point better off, and Deila does not expect Frank de Boer's side to travel to Glasgow with great confidence.
"They have also struggled lately in Europe," the Norwegian commented.
"They haven't won away for a long time, so we have a very good opportunity. It's always very hard to come here to Celtic Park.
"We are going to do everything we can to make it even harder for them and get three points."
"I think that's the same for Ajax as well, they want to win. So it's going to be an interesting game and a big opportunity for us to get a good result and go down to Turkey and do everything for ourselves.
"I think we've been a little bit unlucky in some of the games. Last year I can say we were maybe a little bit lucky, but this year I think we have been a little bit unlucky.
"You can talk about being unlucky, but it's also about being good in the right moments. We have made some stupid mistakes and have lost some important points."
Celtic will be forced to field a makeshift midfield against Ajax, with injury ensuring Scott Brown will join the suspended pair of Nir Bitton and Stefan Johansen on the sidelines. Kris Commons is also a major doubt for the match.
"It is of course more tricky because a lot of the experience is out, but we have good players, players who can fill those roles," Deila continued.
"We have to put together a team that can bring a good performance."
"I really want to succeed in Europe. That's what everybody wants.
"It's nothing to fear. It's a football match that we have a big opportunity in."
Lionel Messi is not the only threat in the Argentina team, according to Switzerland's Admir Mehmedi ahead of Tuesday's last-16 World Cup clash.
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Celtic manager Ronny Deila says his side must beat Ajax on Thursday to keep their hopes of advancing to the Europa League knockout stage alive.