Gayle missed the West Indies' final pool match against the United Arab Emirates on Sunday, but Sammy said he believes Gayle will take his place in the lineup for the quarterfinal. The injured batsman has received a cortisone injection to help with the pain.
"Chris is not missing this quarterfinal for anybody," Sammy said. "He is more pumped up than we are. He's been writing down the path for us and the different scenarios."
Sammy said the teams' records don't count for anything in the knockout stages.
"We always believed from the time the tournament started, the first goal was to reach the quarterfinals. After that, you're two knockout games away from a World Cup final. We've won two, it's been a long time, but New Zealand has not won any," he said.
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"We're not too bad in knockout games. We're just going to enjoy it. The pressure is not on us."
The West Indies last played New Zealand in the knockout rounds of a major tournament at the Twenty20 World Cup in Sri Lanka in 2012. That match ended in a tie and the West Indies went on to win in a super over.
"This time around, it won't be any different -- a full house rooting for New Zealand but we know within our group once we do the basics, the things we know we can do well, we are unstoppable.