With one ferocious swing of a right foot, the water bottle took flight.
Incredulous at a yellow card for world-record signing Paul Pogba, Manchester United boss Jose Mourinho's frustrations boiled over once more.
Sixty-eight per cent possession and 17 shots on goal wasn’t to be enough. West Ham United refused be breached.
And for the second time in a month, Mourinho was sent to the stands, leaving the Old Trafford crowd to watch on as his side slumped to yet another home draw – the first time they had failed to win in four straight league games in over a quarter of a century.
Nine months on, West Ham returned to the Theatre of Dreams to once again be dominated, but this time they couldn’t keep Man Utd out – not with £75 million Romelu Lukaku leading the line.
The former Everton striker arrived in Manchester this summer precisely to ensure there would be no repeat of the profligacy that saw them equal a club-record 10 draws at home last season.
Twice in the first half-hour the Belgium international was denied a tap-in, but on 32 minutes the powerful forward darted across the West Ham backline to receive a Marcus Rashford through-ball to break the deadlock.
The 24-year-old has now scored on his Premier League debut for three different clubs, having previously found the net on bows for West Brom and Everton. And with his goal came a collective sigh of relief, the tension eased.
Five minutes into the second half Lukaku rose to head home his second, sealing a Pressure Index score of 92/100 in a dream debut and, more importantly, sending a clear message that he can give this side the cutting edge they so desperately lacked in Mourinho’s first season in charge.
His team relaxed and dominated completely, Anthony Martial and Paul Pogba sealing a 4-0 rout.
"It's just the start,” beamed Lukaku. “[Mourinho] wants me to be a leader for the team.”
Lukaku led from the front as he shrugged off the pressure of his price tag to deliver what his team need most.
And West Ham must be sick of the sight of him. Lukaku has now scored more goals in all competitions against West Ham than he has against any other English side (11), and gave Mourinho his biggest Premier League win as Man Utd manager.
"We lost two points against West Ham here [last season] and had lots of similar matches where we dominated but did not score enough goals,” Mourinho said. “Today we did and it's three important points.”
Manchester United and Romelu Lukaku are off to a flying start, on an afternoon where they raised expectations, while ensuring the water bottles remained grounded.