Woods is captaining and playing for the United States at the biennial matchplay showdown at Royal Melbourne, and one of Els' key decisions will be who plays the 15-time major-winner in the singles on Sunday.
The big South African has seven rookies in his 12-man team, but he also has a core of experienced players such as Adam Scott, Louis Oosthuizen and Marc Leishman.
Els said he would decide who faces Woods after seeing how they perform in the three days of fourballs and foursomes, but suggested it would not be a newcomer.
"I don't want to have a guy feel overwhelmed," he said in Sydney ahead of the Australian Open, where Els will play from Thursday alongside a handful of his Presidents Cup team.
"I will not put a guy in there that's going to feel that way. I'll see who is going to feel like he's really got the best chance against Tiger.
"I don't think today he has the same kind of aura he had in the past. It's different," added Els, himself a matchplay specialist but will only be captain in Melbourne.
'Not what he used to be'
"It's more of a celebrity kind of aura. But he's still very competitive. He's won the Masters and he won in Japan (both this year).
"When Tiger is healthy, he can play at a very high level. But he's not what he used to be consistently. That's just what age does. But we'll see when we get to Melbourne."
The United States go into the tournament as heavy favourites, boasting some of the world's top-ranked players such as Woods, Dustin Johnson and Justin Thomas.
They have won all but one edition in the event's 25-year history, with Melbourne in 1998 the exception.
Els said he had a good idea of what his pairings would be for the opening day of fourballs next Thursday, without giving anything away.
"There are a couple of pairings that are kind of natural pairings, if you can call it that, but I'm looking at it in a different way, not just a personality way." he said. "I'm looking at how the guys can really perform together.
"I've spoken to the players, some of the players already. So my thing is kind of set already, my plan is kind of set in motion already."
In addition to Scott, Oosthuizen and Leishman, Li Haotong of China, Taiwan's CT Pan, Mexico's Abraham Ancer, Australian newcomer Cameron Smith and Japan's Hideki Matsuyama all qualified automatically.
Adam Hadwin and Jason Day were Els' captain's picks alongside rookies Im Sung-jae and Joaquin Niemann, although Day has since pulled out injured and been replaced by South Korean An Byeong-hun.