Argentine footballer Sergio Aguero scored a hat-trick as Premier League leaders Manchester City escaped a huge FA Cup upset by coming from behind to win 4-2 at home to second-tier Watford.
Beaten Championship play-off finalists last season, Watford went 2-0 up inside 30 minutes through Fernando Forestieri and Troy Deeney to leave free-scoring City at risk of a shock defeat.
However, Aguero struck three times in the last half an hour, with Aleksandar Kolarov also on target, to send last season's beaten finalists into the fifth round.
Liverpool also avoided a potential banana skin by winning 2-0 at second-tier Bournemouth.
Premier League side Crystal Palace were the day's biggest casualties, losing 2-1 at holders Wigan, who were relegated to the Championship after stunning City 1-0 in last season's final.
Sunderland followed up their mid-week success against Manchester United in the League Cup semi-finals by toiling to overcome non-league Kidderminster Harriers 1-0, with Charis Mavrias scoring the only goal in the fifth minute.
Swansea City, Cardiff City, Southampton and Hull City also overcame lower-league opposition.
