"I think it will be an interesting game, a 50-50 game, and both teams are qualified so it will be a unusual game", said Fellaini, who plays in England for Manchester United, having made his name for another Premier League club Everton.
England, however, will gain advantages from finishing second in Group G.
Marcus Rashford and substitute Danny Welbeck went closest to an equaliser on a night when Belgium's second ever win in this fixture left England plotting their route to Moscow.
"We created some good chances".
Perhaps it is a case of damned if he did and damned if he didn't in terms of the changes to his team, but by failing to avoid defeat, have England lost crucial momentum, and have they set themselves up for a fall?
Southgate rested a cluster of players who had been involved in wins against Tunisia and Panama in England´s opening two games in Russian Federation, including star striker Harry Kane.
Now that England have finished second in their group, they will take on José Pékerman's Colombian side without 2014's Golden Boot victor, James Rodriguez, who limped off against Senegal earlier today. "I think we'd shown over the 120 minutes that we were the better team and we deserved to go through".
The Red Devils are unbeaten in their previous 11 World Cup Group matches.
Belgium made 9 changes and England eight as star strikers Romalu Lukaku and Harry Kane were rested.
Opposite number Roberto Martinez is expected to make wholesale changes to his team, with Manchester United forward Romelu Lukaku nearly certain to miss out after picking up an ankle knock in Belgium´s 5-2 win over Tunisia. I can't imagine a situation where I stand in front of the group of players I have got and start talking to them about anything else. Does he make wholesale changes and keep the squad engaged, or maintain continuity with his firing first-team players? That is the reality, we have put ourselves in this situation, we wanted to qualify and we have done that.
Colombia reached the quarter-finals of the World Cup four years ago. Cue the celebrations from the Belgians led by Michy Batshuayi, who picks up the ball, dropped kick it and promptly hits the post and gets smacked right in the face by the rebound. The last-16 ties start Saturday, with France taking on Argentina in Kazan and Uruguay facing Cristiano Ronaldo´s Portugal in Sochi.
Southgate was entirely deadpan as, responding to the first question a few minutes after Kim Young-Gwon and Son Heung-Min scored the goals to knock Germany out, he said: "In this tournament they've been ahead for a minute-and-a-half of their three matches".