Liverpool again failed to beat a side in the top half of the Barclays Premier League table as West Brom registered a fortuitous first win at Anfield.
Steven Gerrard was denied from the penalty spot courtesy of a brilliant save from man of the match Ben Foster in the 77th minute and the Baggies broke the deadlock just four minutes later.
West Brom did not have a shot at goal until Youssuf Mulumbu's sliced effort in the 80th minute produced a great save from Pepe Reina, only seconds later Gareth McAuley powered in a header from the resultant corner.
The imposing Romelu Lukaku then beat Daniel Agger with alarming ease to slam in a second in the 90th minute to complete West Brom's double against Liverpool, following their 3-0 victory on the opening day of the season.
Brendan Rodgers conceded Gerrard's failure to convert his penalty - erroneously awarded after Luis Suárez succumbed to gravitational pull - was the obvious turning point, but the hosts were heavily reliant on the livewire Suárez again.
Daniel Sturridge miserably sat in the stands as injury prevented the forward from adding to his four goals from six games for the Reds. Not only has the England international been an instant success at Anfield, he has alleviated the burden on Suárez, who experienced a fruitless evening.
Raheem Sterling and debutant Philippe Coutinho were both sent on to sharpen Liverpool's blunt attack at 0-0 but minutes later the dithering Agger lost McAuley for the sucker punch.
Rodgers said only last month Liverpool could finish second this season. An outlandish proclamation at the time, Liverpool are now 17 points adrift of Manchester City and West Brom have leapfrogged them after Monday night's result.
Sitting unpretty in ninth, 12 points off of a Champions League berth and eliminated from the FA Cup by Oldham, European football could return to Anfield only via a Europa League triumph in May.