Belgium coach Marc Wilmots has opted for a rotation policy at the FIFA World Cup™, changing his line-up constantly, and has so far given 20 of his 23 man squad some playing time.

While some have questioned whether chopping and changing the starting line-ups has disrupted the Red Devils rhythm and provoked unconvincing performances, Wilmots can point to three straight wins in the group stage.

The 45-year-old former Belgian international striker is expected, however, to spring some more surprises for Tuesday's Round of 16 clash with the United States in Salvador. Aside from a quintet of players, goalkeeper Thibaut Courtois, playmaker Eden Hazard, midfielder duo Kevin De Bruyne and Axel Witsel and captain Vincent Kompany, the other six places are up for grabs.

Wilmots had warned before the finals what his strategy would be.

"I have 23 players. It would be stupid on my part not to use them if they are the right ones to select for a particular opponent," said Wilmots, who has been in charge since 2012. "My starting XI is never the same, because the adversary is never the same sort of team that we faced in the previous match either."

With an hour gone of the match a new player can bring freshness when the opponents are beginning to tire.

Marc Wilmots, Belgium coach

Wilmots, who scored 28 goals in 70 appearances for Belgium, has proved adept at making substitutions at crucial moments like sending on Marouane Fellaini for the second-half against Algeria which saw him score the equaliser before they went on to win 2-1.

He also produced decisive substitutions for the 1-0 win over Russia sending on teenager Divock Origi for a displeased Romelu Lukau. Origi went on to score in that game and also in the 1-0 victory over South Korea, his fresh legs on the hour mark turning the game in the favour of a 10-man Belgian side.

"A lot of matches are decided in the final quarter of an hour," said Wilmots. "But there is often little point in sending a player on in the final few minutes because he doesn't have the time to get into the rhythm of the game.

"With an hour gone of the match a new player can bring freshness when the opponents are beginning to tire. Also the substitute has the time to slot into the game."