Son's expression turned to one of frustration after he was substituted by Richarlison in the 56th minute at the Tottenham Hotspur Stadium. This came shortly after his perfectly placed cross led to Brennan Johnson's equalizing goal. However, manager Postecoglou clarified that Son's substitution was premeditated, taking into account his recent return from injury.
"He was never going to play more than that today because obviously he'd had an injury," explained the Spurs boss in his press conference.
"He came back and last time it was around the 60-minute mark where he got fatigued. So, he was never going to play more than 55-60 irrespective of where the game was going.
"The great thing was he made a pretty important contribution before that. It was a great ball in for our first goal and got our equaliser.
Trending"Again, we've got more battles ahead and we're going to need him and he was never going to play any more than that.
"I didn't see any difference in Sonny. I'd be surprised if any player likes coming off and they're feeling alright.
"I didn't need to discuss it with him. For us, what's more important is the overall picture."
The emphatic win, achieved despite falling behind to Morgan Rogers' goal from a corner, moved Spurs up to seventh, only two points behind fourth-placed Arsenal, and owed a lot to the performance of Solanke, who scored twice before James Maddison's late free-kick.
The striker, a £65m signing from Bournemouth, had not found the net since late September but Postecoglou insisted his contribution is vital even when he doesn't score, as was the case in the 2-1 win over Manchester City in the Carabao Cup on Wednesday.
"He put in an enormous effort on Wednesday night to help us win a game of football, not just physically but mentally, with his capacity to help the team in any way he can," he said.
"To back that up today with such a massive effort against a pretty difficult team to play against in that sense, just unbelievable.
"The goals are great and of course, as a striker, I'm sure he loves the fact that he can score a couple of goals.
"But even if he didn't, I just can't speak highly enough of what he's contributing to our team at the moment. Long may he continue because with him playing that way, he just makes us a better team."
Following the win over City, Spurs have now secured back-to-back wins over top-four opposition following last Sunday's 1-0 loss to Crystal Palace.
"You don't fall off cliffs and you don't climb mountains within a week. It's all part of the same process for me. We're going to have bumps along the way.
"It's how you address them, how you cope with them, how you rebound and learn from them.
"That's the key thing. We had a disappointing day last Sunday but we knew coming in on Monday we had two big games this week, really important games.
"So, no points for feeling sorry for ourselves. We had to come in and get our heads straight and work back towards being the team we want to be.
"That's what happened but it that's the end of it now. We've still got to push on, we've still got to get better, we've still got to improve and keep pushing on."