Hakim Ziyech says Morocco found it "easier" to face Belgium than Croatia after they moved top of World Cup Group F with a 2-0 win over the Red Devils.
Belgium were favourites to secure what would have been a record ninth consecutive victory in a World Cup group game at Al Thumama Stadium on Sunday.
Morocco were worthy winners, though, following up a goalless draw with Croatia by taking all three points in Doha.
Romain Saiss got on the end of Abdelhamid Sabiri's set-piece to open the scoring and Zakaria Aboukhlal sealed a famous victory for the Atlas Lions in stoppage time.
Ziyech was named man of the match after having a first-half goal disallowed for offside and providing an assist for Aboukhlal in the closing stages.
The Chelsea winger said: "The first game was more difficult for us. We couldn't play our game, Croatia played a very good game. This one was perhaps easier, especially in midfield. They may have made more mistakes than the Croats.
"We played a very strong, robust game, especially in defence. We were waiting for their mistakes and I think we took the lead from that and scored at the right time."
Ziyech added: "I don't deserve this player of the match trophy. It's a collective effort, everyone was behind me, it's a collective work."
The former Ajax man felt Morocco's vociferous fans played a big part in a huge win in the battle for a place in the round of 16.
He said: "After 60-70 minutes some were tired and when we scored that goal they rallied behind us. It gave us more power, more power. The crowd helped us, they were behind us and I think that really boosted us."
Morocco’s victory over Belgium was their first in five World Cup matches and put their fate in their own hands heading into a final group game against Canada next Thursday.