The Dutch midfield ace came up against the Spanish side in the Champions League the season after they were pipped to the La Liga title by Real Madrid.
It came in the group stages of the 2003-04 competition in what turned out to be Edgar's last season at Juventus.
"We didn't know Real Sociedad very well at the time, played against them and they were very good," recalled Edgar at Spurs Lodge. "We didn't expect that.
"I was up against Xavi Alonso (now of Liverpool) in midfield and he surprised me as well, an excellent player.
"It was a tough couple of matches, we drew there but beat them at home." Indeed, Juve beat Sociedad 4-2 at home after a goalless away draw - both teams progressed but crashed out in the last 16.
Edgar moved to Barcelona in January 2004 and was credited with helping the Catalan giants back on the road to success. Mid-table when he joined, Edgar's arrival coincided with a storming end to the 2003-04 season as Barca finished second in La Liga, including a 1-0 home victory over Real Sociedad in March 2004.
"I didn't feel any particular rivaly between Barcelona and Real Sociedad," said Edgar. "That game was at the Nou Camp and I didn't feel anything special in the atmosphere. It was another hard game though."
Sociedad have struggled to match their second spot of 2002-03 in recent La Liga seasons and finished just above the relegation zone last term.
"That can happen in La Liga," added Edgar. "You only have to look at Celta Vigo, who we played in France. They played in the Champions League in the season I played for Barcelona but they went down at the end of that season. It's a very strong league.
"When I played against Sociedad they played with a big striker and tried to hit us on the counter-attack and perhaps that's how they will play this time."
Edgar Davids admitted he was taken by surprise when he first encountered Saturday's friendly opponents Real Sociedad.