Lincoln City produced a huge FA Cup shock to beat top-flight Burnley 1-0 away and become the first minor league club to reach the quarter-finals for 103 years on Saturday.
On a day of fifth-round toil for the top flight sides English champions Leicester City's problems continued to mount as they went down 1-0 at third-tier Millwall, who played most of the second half with 10 men.
Middlesbrough were the only Premier League side to guarantee a quarter-final slot, quelling a comeback by third-tier Oxford United to win 3-2 at the Riverside Stadium.
Manchester City were held 0-0 at Championship side Huddersfield Town.
Chelsea are in action later on Saturday at Wolverhampton Wanderers while holders Manchester United face Blackburn Rovers on Sunday when Tottenham Hotspur go to London rivals Fulham.
Millwall's third win over Premier League opposition this season, secured by Shaun Cummings's late goal, would ordinarily have topped the shocks, but they were outdone by Lincoln.
Sean Raggett's headed goal in the 90th minute continued the run of the National League (fifth tier) leaders who easily matched Burnley, a side 81 places higher up the English football ladder.
"It's a football miracle for a non-league team to be in the last eight," Lincoln's young manager Danny Cowley said.
"We are realists. I will never ask the players to do something they're not capable of. But we thought if we could get the game plan right we could compete."
The visitors should have taken an early lead when Jack Muldoon fired over.
Burnley, with only three defeats in their previous 29 home matches in all competitions, struggled to make their higher status show until the latter stages when they finally began to pile pressure on a tiring Lincoln side.
But just when it seemed the Premier League team would make their possession count, Lincoln were awarded a corner and Raggett rose above a crowd of players to head the ball over the line despite keeper Tom Heaton's attempt to claw it out.
Incredibly Lincoln are not the only minor league side to enter Sunday's draw with National League rivals Sutton United hosting Arsenal on Monday.
