David Bentley missed a sitter as West Ham dropped points on their travels for the first time this season after a bruising goalless draw at Millwall.
The Hammers made the short trip across the Thames to face their bitter rivals on the back of three straight away wins and looking to go top of the npower Championship, at least temporarily, following their noon showdown.
But they could not find a way past the Lions with on-loan Tottenham winger Bentley blowing the best chance of the afternoon on only his second appearance.
Henri Lansbury also had an effort cleared off the line but Millwall missed plenty of chances too, with Liam Trotter the main culprit, as a fixture traditionally not for the faint-hearted ended all square.
Millwall have been eagerly awaiting the renewal of hostilities, so much so that some fans chartered a plane to fly over Wigan's ground trailing a banner with the words 'Avram Grant, Millwall Legend' as the Hammers' relegation was confirmed last season.
And while the atmosphere crackled, there was thankfully no repeat of the crowd trouble which marred the Carling Cup meeting between the sides at Upton Park two years ago.
There were plenty of casualties on the pitch, though, with James Tomkins limping off, Julien Faubert spitting out blood after a whack from a stray elbow and Tamika Mkandawire bandaged up with a head injury - all in the first 20 minutes.
But Grant's replacement, Sam Allardyce, has added the steel the Hammers were evidently missing last term as the teams went toe-to-toe in a fiercely contested encounter.
The match got off to a comical start, although Lions manager Kenny Jackett was not laughing.
Straight from kick-off, Lansbury looked up and saw home goalkeeper David Forde adjusting the net behind his goal, apparently unaware the game had begun.
Fortunately for Forde, Lansbury's 40-yard shot flew just wide of the empty goal as the keeper sheepishly jogged back into position.
But Millwall recovered from that shaky opening and came close to scoring three times in the first half.
Mkandawire put a header narrowly wide and Trotter shot too close to Robert Green before hooking a volley over from six yards just before the break.
By then West Ham had also been denied, in spectacular fashion, after Forde initially made a meal of coming for a corner.
He got up in time to keep out Lansbury's shot and when the ball fell back to the midfielder his second, fierce effort was bravely headed off the line by Paul Robinson.
In the second half Lansbury floated in a dangerous cross but Forde held Kevin Nolan's diving header.
Bentley's big moment arrived in the 75th minute when Faubert's low shot was palmed across goal by Forde.
But the former England winger, looking to become the first West Ham player to hit a winner at Millwall since Paul Ince some 23 years ago, somehow dragged his effort wide.
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