Scotland coach Craig Levein admits he waited too long to make substitutions in Scotland's 0-0 draw with Serbia, reports BBC Sport.
"I maybe should've gone a wee bit earlier," said Levein after the opening World Cup qualifier at Hampden.
"We got out of this game with a draw. It's not what we wanted, but it's certainly not a disaster.
"I was toying with the idea of bringing Shaun Maloney on at one point but then decided to go with putting the two strikers on.
"There's loads and loads of options. Sometimes they work for you, sometimes they don't. I thought they made a difference, but we didn't get the victory.
"Disappointed we didn't win, that's my overriding feeling. We created enough chances to win the game and the disappointing thing was we didn't."