Fred does not believe Manchester United were even at their best in December's remarkable 6-2 thrashing of Leeds United as he fired a warning ahead of a rematch of what he calls an "English football Clasico".
United and Leeds were once party to one of the fiercest rivalries in British football, but it took a backseat to the Red Devils' other major matches after the Yorkshire club were relegated from the Premier League in 2004.
The December meeting at Old Trafford was their first in the league for over 16 years, but for Leeds it swiftly turned into a nightmare as Scott McTominay became the first player in Premier League history to score twice in the first three minutes of a match.
That was just the tip of the iceberg, however, as Leeds went on to concede four goals in the first half of a Premier League fixture for the first time, Bruno Fernandes and Victor Lindelof increasing the lead before Liam Cooper pulled one back.
Fernandes converted a penalty in the second half shortly after Daniel James netted, with Stuart Dallas' goal at the other end scant consolation.
Although it was the first occasion a Marcelo Bielsa team had conceded six goals in a game since 1992 and the first time United had scored so many since an 8-2 win over Arsenal in August 2011, United still allowed Leeds 17 attempts.
"I don't know if it was our best performance of the season, [but] 6-2 was a great result of course," Fred told United's official website. "I think we've had better performances this season.
"Scott's two goals very early on helped us to control the game, but they're very difficult opponents playing with such high intensity, they're very strong and always looking to attack.
"We're prepared for this, we know how they play and we'll aim to be at our very best to get the win."
Ordinarily United would be entitled to a rather frosty reception at Elland Road, though the absence of fans amid the coronavirus pandemic means they will avoid the worst of it.
Fred is certainly familiar with such occasions as a veteran of several 'Grenal' matches between Gremio and Internacional, a match that in December was ranked as the eighth biggest derby in world football.
"Definitely, it's an English football Clasico," he said of fixtures between United and Leeds. "We get a feel for this anticipation from social media.
"The fans are excited about this game, as are we of course. We haven't had a midweek game this week, so the anticipation for the next game increases and it's a derby game against a massive rival.
"It'll be a really tough game but we'll be preparing well for it this week."
Sunday's clash will be United's first visit to Elland Road since October 2003, a 1-0 win – they have not won successive league games at Leeds since 1976.
Nevertheless, Ole Gunnar Solskjaer's men are unbeaten away from home in the top flight for over a year, a run consisting of 23 games.