Second half strikes from Craig Ellis and James Gershfield saw Team GB boost gold medal hopes with a 2-0 victory over an ill-disciplined Mexico team who finished with eight men after three reds cards.
GB were on top throughout in a victory marred by an injury to right-back Danny Cole who suffered a broken arm and is out of the competition.
With Daniel Stanton suspended, GB manager Ben Winston drafted George Fierstone into the starting XI in a must-win game for GB.
GB looked nervous in the opening exchanges with the Mexicans coming close with a free-kick that drifted fractionally wide.
Aron Barnes, who is having an impressive tournament, surged forward at every opportunity and it was his free kick that Ellis glanced a header just wide.
Then Gershfield, a hat-trick hero from the opening day win over Belgium, tested the keeper with a free kick that was comfortably held.
GB looked polished as the half wore on with a floated corner from Ben Lauffer was met by captai Guy Morris whose header forced another save.
With the half time whistle approaching, the ball fell to Daran Bern on the edge of his box and his snapshot was pushed around the post by the keeper.
GB went into the break by far the happier against a Mexico team who soaked up lots pressure, knowing a draw would leave GB needing to score at least 13 goals in the final group match against Austria.
Winston’s troops got the goal their pressure deserved seven minutes into the second half. A pinpoint delivery from the right by Lauffer was headed into the top corner by Ellis who was one of the outstanding performers on the day.
Mexico stepped up their game but it was GB who doubled their lead around the hour mark a Mexico corner was cleared to Fierstone. The youngster broke downfield before slipping a delicious past to Gershfield who stuck the ball past the keeper from a tight angle for his fourth goal of the tournament.
With a two-goal cushion in their favour, GB manager Winston brought on Paul Babai for Fierstone who had looked the part. Bern was next to be replaced with TJ Keterman coming on.
The Mexicans started to feel the heat at they were reduced to 10 men after their left-back received his marching orders following a second yellow card.
Ten became nine minutes later as a Mexican reacted badly to a strong but fair challenge by Ellis.
Gershfield went close again after a Cole whipped over an inviting cross. Cole, Aron Barnes, David Soutar and Morris were outstanding at the back as the Mexicans were kept in check.
Not content to sit on their lead, GB continued to go forward with a great longfield pass from Soutar finding Gershfield whose low cross was met sweetly by Keterman but the keeper was on hand to block.
The only negative of the match came in the last 15 minutes when Cole was rolling around in agony by the corner flag after an awkward fall. It was later confirmed that he had broken his arm and he needed oxygen while waiting for an ambulance.
Mexico had lost their heads by this point with a third player dismissed after a late and dangerous lunge on Morris who did well to get back on his feet immediately.
GB’s professional display saw them finish with 11 men for the first time in a game where their discipline was of the highest order.
Craig Ellis forced the Mexico keeper into another save from a low 20-yard drive and as the final whistle blew, GB knew that it was job done.
With Mexico having completed their programme, GB will reach the final if they avoid defeat against Austria tomorrow evening.
Delighted GB manager Ben Winston said: “We knew we had to win the game as a draw would not have been enough today. Everything went to plan. It was about keeping calm and not panicking.
“We started the match nervously but went on to dictate against a very good Mexico team. I half time I told the boys that they were knocking on the door.
“Their game-plan was to try and upset us but it got a bit silly towards the end.”
“Mexico’s No. 10 plays in the top league in Mexico but we defended heroically and we kept the ball well. We popped the ball around quickly and played at a high tempo.
“We responded perfectly after going ahead and there were great performances all over the park. I have nothing to complain about.”
Winston believes his decision to start Fierstone was vindicated. "George was incredible today. He played the perfect match. It was a bold move to start a 17-year-old but I was very proud of his performance.
“Paul Babai is a remarkable guy. He steadied the ship when he came on and is having a great tournament.
The win saw GB make it three out of three. Looking ahead to tomorrow’s clash against Austria, Winston commented: “We need a point to go through tomorrow. Austria are the weakest team in the whole competition.”
Winston paid tribute to Cole. “The boys are very upset. A couple of them were very distressed when I told them what Danny had done. Danny is one of the most popular boys in the squad so if we can go on to win gold we will do it with him in mind and put a gold medal around his neck.”
Team GB: Matt Davis 8, Danny Cole 8, Aron Barnes 9, David Soutar 10, Guy Morris (capt) 9, Craig Ellis 9, Ben Lauffer 8, George Fierstone 8, Daran Bern 8, Matt Stock 8, James Gershfield 8. Subs used: Michael Sacks 7, Paul Babai 8, TJ Keterman 8, Ben Ellis 7, Adam Stolerman 7. Sub not used: Dan Lee
Goals: Craig Ellis 52, James Gershfield 58
Booked: Bern 6
JC Match Stats
GB
Shots:
On target: 7
Off target: 3
Corners: 8
Fouls: 9
Offside: 2
Cards: 1
Yellow: 1
Red: 0
MEXICO
Shots:
On target: 1
Off target: 5
Corners: 4
Fouls:8
Offside: 0
Cards:
Yellow: 6
Red: 3