Morata was forced off early on in the 1-0 defeat to Manchester City before the international break.
But Conte decided to replace the striker with winger Willian, despite having a forward in Michy Batshuayi waiting on the bench.
And Le Saux reckons Conte overlooked Batshuayi in case he needed a super sub later on in the game.
The Belgian was brought on 73 minutes with Chelsea a goal down at Stamford Bridge but failed to find his side an equaliser.
Betfair ambassador Le Saux said: “When Morata was subbed, I wrote Michy Batshuayi’s name on my team-sheet as the replacement.
“So I was as shocked as anyone else to see Willian come on in his place.
“All I can think is that Batshuayi doesn’t quite have the big game experience under his belt yet that Willian does.
“In addition, the Brazilian probably offers more from set-pieces and in one on one situations.
“But his natural propensity to sit deeper than Morata does invite City pressure on and again goes to show how important the Spaniard is to Antonio Conte.
“Also, the substitution was fairly early in the first-half.
“So perhaps the manager had it in his mind that he could still utilise his ‘super sub’ if needed later in the game.”
