SUNDERLAND are 1-0 down at half-time here against opponents who took a lead just before the half-hour.
Tricky Brazilian midfielder Everton Santos did the damage with a successful one-two in the Sunderland penalty area before steering a low shot around the exposed Simon Mignolet from five yards out.
Sunderland were playing in their new home strip for the first time as Martin O’Neill set out a 4-5-1 formation which became a 4-3-3 when the Black Cats were on the attack.
Wes Brown and Jack Colback were the full-backs, Fraizer Campbell and Kieran Richardson the wingers with Connor Wickham the lone striker.
It was the South Koreans who made all the running in the opening few minutes as Sunderland looked to settle into unfamiliar surroundings and conditions.
Defender Namgung Woong drove a shot wide from range but there was much more danger in the sixth minute when Titus Bramble failed to pick up from a right-wing corner and centre-half Lim Jongeun powered a header wide.
Gradually Sunderland got a foothold.
Striker Park Seyoung picked up a ninth minute yellow for a foul on David Meyler in what was the Black Cats’ first attack of the game, then the Wearsiders earned two corners in quick succession and Kieran Richardson headed the second one wide.
The surge was not to last though and midway through the first-half Seongnam twice came close to breaking through.
First, the lively Santos came desperately close to getting on the right side of a one-two in the Sunderland area and then Campbell was flummoxed in the right-back position and grateful to see the close-range cross lack quality.
The South Koreans took the lead though in the 29th minute when, this time, a Santos one-two did come off, exchanging passes with Javier Calvo before curling a confident shot around Mignolet from five yards out with the Belgian unable to defend the shot at his left-hand post.
Sunderland could have no complaints – Michael Turner had made a last-ditch block in his six-yard box a couple of minutes earlier and Mignolet made a brave save at the feet of the goalscorer a couple of minutes after the lead was taken.
Sunderland looked to be pacing themselves, content to hold the ball and choose their attacking moments.
They created another good chance in the 40th minute when Meyler centred to Richardson at the far post but the defenders’ first-time volley from the left, eight yards out, flashed over and he was out of luck with another thrash with virtually the last kick of the half.
Half-time: Seongnam 1 Sunderland 0
Sunderland: Mignolet, Brown, Bramble, Turner, Colback, Meyler, Cattermole, Gardner, Richardson, Campbell, Wickham. Subs: Wilson, Pickford, Egan, Adams, Cuellar, Laing, Knott, Vaughan, Reed, Deacon, Noble, Lynch.