Rusk took charge after the dismissal of manager Russell Martin earlier this week.
After last night's 2-1 defeat at St Mary's, Rusk said: "I think the first half, our priority going into the game was to be hard to beat, given the nature of the game on Sunday.
"I think probably expected in some way, shape or form that we might not have the footprint in the game we want in the first half.
"I think our priority was getting into half-time and making sure we're in the game as a basic principle, and then growing into it.
"The nature of the first goal is a bit unfortunate. I thought in the second half the guys stood up to it, didn't wilt and maybe on another day we'd nick a second."
On his personal approach to the tie, Rusk also said: "It was myself, as normal. I spoke the other day about running my own process for a game. I'd always give the players space at the start of the break.
"They understand the feeling and where they're at, how we feel the game's plan going. Then we discuss what's going to be important in the next 45 minutes.
"So from my point of view, it was business as normal. I listen to players but ultimately I direct it where I think it needs to go."
On his message to the players, the caretaker manager also said: "I don't think it was about the players in a black-and-white fashion telling me what they want from the game.
"Obviously, they were hurting from the other day and without a doubt they need some form of leadership and direction and obviously, that's my job.
"But I think it was important for me to understand where the group was at physically and mentally, probably more than where we were at tactically.
"We devised a game plan from there to be very hard to beat and that requires bodies and then be good on the counter.
"There wasn't much time to turn this game around and you can only work on so much, you can't overload them with information when there's change anyway.
"I'm really encouraged by the second half. That's what we have to focus on now. They showed belief in themselves, they showed character, they stood up.
"The fans were behind them as a result and I think hopefully that second half is enough of a catalyst for the guys."