Neil Harris is "delighted" with how much Millwall have improved since the 5-3 defeat at Peterborough earlier this month.
Harris' side kept their fourth consecutive clean sheet at The Den in a bruising contest with Bradford that moved the Lions up to seventh place in the Sky Bet League One table.
Shaun Williams had the best chance to seal the three points for the home side but Ben Williams in the Bantams goal produced a superb reaction save to tip his shot over the bar.
There were few other chances between two well-drilled sides as Millwall extended their unbeaten run to six games in all competitions.
Millwall shaded the second period but couldn't break through a resolute Bradford defence. The Bantams could have taken a first-half lead when Devante Cole scooped a half-chance over the bar.
James Hanson, who was a target for Harris in the summer, also looked like he would be a danger for the afternoon after a bright start, but Tony Craig and Mark Beevers eventually nullified his threat as Millwall pressed higher up the pitch after the break.
Craig went off injured in the second half after what Harris described as a "brilliant" block on Hanson's shot from outside the box and the Millwall boss said the extent of the defender's injury isn't yet known.
Harris was pleased with his side's overall performance and striker Steve Morison's display, but felt tiredness was a factor in failing to work Williams on more occasions.
He said: "I'm delighted with the clean sheet, the effort, determination, the defending was fantastic at times, but maybe we just lacked a little bit of quality, all over the park, really. We lacked a little bit of composure.
"We put a lot of balls into their backline and into their box and I thought Steve Morison put in a terrific performance as a target man today, used his experience well, won a lot of flick-ons, a lot of knockdowns.
"But as a team I thought we weren't always proactive onto the next ball, we were a little reactive. Maybe it was a sign that it was just a game too far for a few of the bodies today.
"But on a whole I'm delighted with a clean sheet and a point and how far we've come since October 3 at Peterborough."