LONDON (REUTERS) - A brilliantly taken goal by Demba Ba gave Chelsea a 1-0 win over Manchester United in an FA Cup sixth-round replay at Stamford Bridge on Monday, securing the holders a semi-final against Manchester City.

The Senegal international, who had scored only once for Chelsea in his previous 10 appearances, struck in the 49th minute when he allowed a lofted ball from Juan Mata to drift over his shoulder before stretching to volley it into the far corner beyond a helpless David de Gea.

A stunning save from Chelsea's Petr Cech 14 minutes later was the other highlight of an otherwise relatively tame game, the 'keeper acrobatically stretching back to tip a header from Javier Hernandez over the bar.

Chelsea, who have won the Cup four times in the last six seasons, will meet City, the 2011 winners, at Wembley on April 14.

Championship (second tier) side Millwall will meet Premier League side Wigan Athletic in the other semi-final at Wembley the day before.