Sakho finished off great work
from fellow substitute Arthur Masuaku, who did terrifically to set him up for the winning goal.
Jordan Ferri doubled the advantage in the 88th minute, shortly after replacing Maxime Gonalons,
before fellow substitute Corentin Tolisso netted in the 90th minute.
Fellow substitute Glenn Murray assisted him, chesting a direct ball directly to him in stride, and he hit a finish as cool as the one for his first.
The striker had only been on the pitch seven minutes but he combined
with fellow substitute Marc Albrighton to nod in the winger's cross from six yards.
On 90 minutes, substitute Christian Benteke knocked down a Jordan Henderson long ball into the path
of fellow substitute Allen, who turned the ball home to send Anfield wild.
«The fresh legs of Gana and
[fellow substitutes] Beni Baningime and Dominic Calvert - Lewin gave us more in terms of our energy and attacking prowess and that is why we finished the game so strongly,» added Allardyce, who is still without key playmaker Gylfi Sigurdsson and long - term absentee James McCarthy.
Tito Vilanova then threw on David Villa to
join fellow substitute Alexis Sanchez in a bid to find the winner and Sanchez produced the killer cross for Messi to head home his second of the evening with 10 minutes remaining.
Bellerin slid the ball just wide from Ozil's delightful ball over the top of the defence, before Giroud made it 3 - 0 with a superb curling effort from inside the box after being found
by fellow substitute Alex Oxlade - Chamberlain.
Aaron Ramsey completed the scoring to hand the Premier League side a scoreline that probably flattered them when he dashed
onto fellow substitute Olivier Giroud's cushioned header to lift the ball over the exposed Megyeri with seconds remaining.
Conor McAleny wasted a golden opportunity to level eight minutes from time
as fellow substitute Wes Burns» deflected shot fell to him at the back post but he cannoned the ball wide as Fleetwood slipped to a third successive home league defeat.
Marcus Rashford surged into the penalty area before cutting back onto his right foot and teeing up
fellow substitute Mata, who curled a first - time shot beyond Randolph's left hand and into the top corner.
Manager Eddie Howe responded to the two - goal deficit by bringing on England striker Jermain Defoe for his first appearance since he suffered a fractured ankle in December, but it was
fellow substitute Smith who put them back in the game.
Depoitre, a late replacement for Steve Mounie, headed brilliantly home in time added on from
fellow substitute Florent Hadergjonaj's excellent cross.
After Jese complained in animated fashion about not being given the chance to do so, it was
fellow substitute Charlie Adam who took the penalty, and saw his effort from 12 yards saved by Mathew Ryan.
This was a risk: Coquelin moved to right - back against Young, United's most dangerous attacker, while Walcott stayed high up the pitch, running in
behind fellow substitute Tyler Blackett.
But Jhon Cordoba equalised seconds after coming on, before
fellow substitute Levin Oztunali scored the winner to give Mainz their first - ever Europa League victory.
Like
his fellow substitutes, Cisse scored in the shootout.
However, the players themselves seemed totally fine as they warmed up among
their fellow substitutes at Turf Moor.
United's goals came through a terrible error by Wigan goalkeeper Jussi Jaaskelainen at the start of the second half who effectively gave the ball to substitute Juan Mata who was able to stroll forward and pass it to
fellow substitute Will Keane for an easy tap in.