By Rob Bishop from Upton Park
Villa were left cursing the yellow peril as they suffered an opening day setback at the hands of Barclays Premier League newboys West Ham.
Paul Lambert's men were clearly confused by a linesman's raised flag before skipper Kevin Nolan tapped home the Hammers' winner five minutes before half-time.
It was a bitter blow for the new boss, who gave debuts to summer signings Ron Vlaar, Brett Holman, Karim El Ahmadi and Matt Lowton.
The visitors produced plenty of attractive football but were unable to find the cutting edge which might have yielded a point.
Despite sweltering heat, both sides displayed plenty of enterprise from the outset, even if clear-cut chances were at a premium during the opening half hour.
Aussie midfielder Holman wasn't far off target with an early left-footer from 25 yards, although El Ahmadi might not have been so happy with a long range effort which was well over the bar.
The Dutch-born Morocco international did better in the 22nd minute when he moved on to Stephen Ireland's well-measured pass and struck a low right-footer which was blocked by former Villa defender James Collins.
Vlaar had to go off for treatment in the 32nd minute, returning with his head bandaged - and it was very nearly a costly absence.
While he was receiving attention on the touchline, Matt Taylor struck a firm free-kick which, thankfully, took a deflection away from goal, with keeper Shay Given committed to his dive.
Vlaar's foul on Carlton Cole led to a free-kick which Nolan fired not far wide as the home side began to get on top.
But there was still a massive sense of injustice when Sam Allardyce's men went ahead.
A linesman's flag was raised as the ball reached Ricardo Vaz Te beyond the far post following a deep free-kick and Villa defenders momentarily switched off, allowing Nolan to tap in from close range.
Video footage indicated that the ball had flicked off Ciaran Clark's head, playing Vaz Te onside, but it was still tough on the visitors.
For all the attractive approach work, neither keeper made a direct save throughout the opening period.
That was rectified within a minute of the re-start, Holman's quickly-taken throw enabling Ireland to hit a hard low drive which Jussi Jaaskelainen saved at the foot of a post.
Although Cole felt he should have had a penalty when he was challenged by Vlaar, Villa's Dutch defender wasn't far away at the other end when he drilled a low shot wide following Charles N'Zogbia's short free-kick 30 yards out.
Just past the hour mark Andi Weimann replaced Holman and the Austrian almost immediately set up a chance, playing the ball into the path of N'Zogbia, whose angled drive deflected for a corner.
There was a scare on 65 minutes, though, Nolan finding space for a low shot which was blocked in a crowded goalmouth after Vaz Te had slipped past Nathan Baker to produce a dangerous low centre.
Cole was cursing on 77 minutes, misdirecting his header wide from an inviting position, although in between times Vlaar's 25-yarder was well held by Jaaskelainen following a fine Villa move involving Ireland, skipper Darren Bent, Weimann and Fabian Delph.
As Villa pressed forward in search of an equaliser, they were caught out by a counter attack in stoppage time, sub Modibo taking the ball past Given before Baker slid back to clear off the line.
West Ham: Jaaskelaianen; Demel, Collins, Reid, McCartney (O'Brien, 71); Vaz Te, Diame, Noble, Nolan (Tomkins, 73) Taylor; Cole (Maiga, 81). Unused subs: Henderson, Diarra, O'Neil, Maynard, Maiga.
Villa: Given; Lowton, Vlaar, Clark, Baker; El Ahmadi, Delph (Bannan, 77) Ireland, Holman (Weimann, 61); N'Zogbia (Gardner, 73); Bent. Unused subs: Guzan, Herd, Lichaj, Burke.