Dagenham & Redbridge forced a replay after Millwall wasted a string of chances to book their place in fourth round of the FA Cup.
Paul Robinson flashed a header narrowly wide while Harry Kane was also denied by Daggers keeper Chris Lewington.
Liam Feeney also went close for the Lions, but Dagenham held out to earn a replay at the New Den.
The League Two club finished strongly and went close to winning it after Billy Bingham let fly from distance.
Dagenham, sitting in 22nd spot in the basement division, will be satisfied with the outcome.
They were missing 11 first-team players and manager John Still gave a debut to on-loan West Ham midfielder Ahmed Abdullah.
Millwall started strongly but were unable to make their chances count.
Robinson, who missed out playing in the 2004 FA Cup final against Manchester United because of injury, went close to making a 20th-minute breakthrough with a header from James Henry's corner.
England under-19 striker Kane, on loan from Tottenham, also caused the Daggers defence problems.
Kane forced an early save from keeper Lewington before Feeney flashed a powerful effort narrowly wide.
Dagenham had their moments and Femi Ilesanmi fired narrowly over the bar before Bingham's long-range attempt.
Millwall manager Kenny Jackett told BBC London 94.9: "I am not displeased with the result because it is a potential cup upset. We live to fight another day and we take Dagenham back to the Den a week on Tuesday.
"We struggled today in Dagenham's half. We had lots of the ball but we didn't do enough with it. When we did get several good balls in, we didn't get on the end of it.
"We lacked confidence, imagination and finishing today.
'We have only scored one goal in four games - that tells its own story - but we have another third round opportunity at home to Dagenham. We didn't take the one today but we have got another chance."