While Guardiola is arguably football's most famous coach, Wild is still making his way in the managerial game and was Oldham's youth team manager until Boxing Day, when he was asked to take temporary charge of the first team following the firing of the manager after a 6-0 loss.
The 33-year-old Wild accepted the challenge, led Oldham to back-to-back league wins and has now overseen one of the biggest FA Cup shocks in recent years.
"It's Roy of the Rovers stuff," said Wild. "It's one to savour."
Fulham led 1-0 with 14 minutes left, only to concede goals to Sam Surridge and Callum Lang. Lang's 88th-minute winner came moments after Fulham striker Aleksandar Mitrovic had a penalty saved off his first touch after coming on as a substitute.
"I did not see desire or passion," said Fulham manager Claudio Ranieri. "I wanted to see desire - show me I am wrong, show me. I am not wrong."
Another of the day's big upsets was also plotted by a caretaker manager.
It was an emotional afternoon for Darren Currie, who led Barnet to victory over Sheffield United - the club where his uncle Tony is regarded as a legend and has a stand named after him at the Bramhall Lane stadium.
"Naturally, he'll be hurting," Darren Currie said. "He wants his team to go through but he's proud of me and what I've done."
Shaquile Coulthirst scored the only goal of the game, from the penalty spot, to ensure Barnet will be the only non-league side among the 32 in the fourth round. Barnet are 15th in the fifth-tier National League.
Sheffield United, sitting third in the Championship, could end up replacing Fulham in the Premier League but the clubs were united in misery yesterday.
Nearly a year after holding Tottenham to a 1-1 draw in the FA Cup fourth round, Newport got the job done against another Premier League team. It felt like history was repeating when Rachid Ghezzal equalised for Leicester in the 82nd minute - the same minute Harry Kane drew Tottenham level 12 months ago.
But this time, there was another twist, as Leicester midfielder Marc Albrighton gave away a penalty for hand ball and Padraig Amond converted from the spot.
Sixth-tier Woking lost 2-0 at home to Watford.
- AP