Willum Willumsson's first-half goal was enough to give Birmingham City victory over Sutton United and take the League One leaders through to the second round of the FA Cup.
Willumsson scuffed Paik Seung-ho’s left-wing cross beyond goalkeeper Jack Sims and into the far corner of the net.
Jayden Harris had an opportunity to equalise for the National League side shortly before half-time.
He did well to pounce on Paik’s poor pass to Ben Davies and galloped from inside his own half towards goal only to then shoot wide of the target.
Ashley Nadesan missed a late chance for Sutton when his poorly-struck volley bounced up off the ground and onto the top of the net.
Sims produced a fine stop in the second half to keep his team in the tie when Ethan Laird pulled the ball back from the right to Harris, whose first-time shot was well saved.
A second goal at that stage would have eased the pressure on Birmingham, who were competing in the first round of the competition for the first time in 30 years.
Sutton, always associated with their sensational FA Cup victory over then top-flight club Coventry City in 1989, kept battling until the end but lacked quality in the final third of the pitch.
Sutton United head coach Steve Morison said:
“It was always going to be a tough ask. We were still in the game right at the end and nearly got that moment. It was a tight game.
"It’s a credit to the players that we just played Birmingham, who outspent Manchester City in the transfer window and outspent their league by £20m, to still be in the game at the end.
“We put a plan in place. We were out to frustrate, we couldn’t go toe-to-toe with them because we wouldn’t have been able to. There are levels to this game. I’m really proud of the players.”
Birmingham boss Chris Davies said:
“We were far superior in the game. We just couldn’t get that second goal to take that margin away from them.
“It was never going to be straightforward and easy, but we controlled it well.
“We managed to keep them at arm’s length and that was important. I thought we handled the game well.
“It’s a big game when we go to opposition grounds, but I say to the players that it should be no bigger a game for them than it should be for us. We are playing for a massive club and need to be ready all the time.
“It’s been a good start to the season. It’s just a start, but we’ve got good momentum.”