Michael O'Neill admitted a "sense of relief" after Northern Ireland left it late to beat minnows San Marino 3-0 on Friday.
Northern Ireland were frustrated by the 204th-ranked home side before Josh Magennis finally broke the deadlock in the 70th minute.
Magennis scored again shortly afterwards before Steven Davis added a third from the penalty spot.
Northern Ireland manager O'Neill told Sky Sports: "We were so dominant from the first whistle to the last and when you have nothing to show for it at half-time you worry you might get a little bit anxious, but we didn't.
"We played very well, with good intensity, and the supporters played a big part. It was about making the breakthrough, we did everything but score in the first half. Once we got the first goal we were comfortable."
The win sees Northern Ireland strengthen their position in World Cup Qualifying Group C with three games left to play.
If they avoid defeat against Czech Republic at Windsor Park on Monday they will be assured of a top-two finish.
"How they played tonight will give them great confidence and they are looking forward to the game on Monday," said O'Neill.
The Northern Ireland boss also praised Magennis' display, saying: "He has been fantastic and he deserves all the credit.
"He has got such an appetite for the game and desire to learn. He did great on the right and then got two goals when he went through the middle.
"He has a willingness to compete and improve. We have seen that an international level and I am sure his club [Charlton] have seen that too."