"Keep going until the final whistle" is an old football adage that makes sense in theory, but is hard to do when you're 4-0 down, your own fans are yelling abuse at you and you're wishing you hadn't turned up.
But, "it only takes a second to score a goal" is another one - and how true it is, as a goal can change everything, and no game is won until it's all truly all over.
We've picked out 10 of the most astonishing comebacks in football history. Lazarus had nothing on these matches.
Reading 5-7 Arsenal (2012)
Like many of matches on this list, you have to feel sorry for the losing side. Reading played magnificently for 44 and a half minutes, putting Arsenal to the sword and going 4-0 up in this 2012 League Cup tie. But a Theo Walcott goal on the stroke of half time proved the turning point. Giroud made it 4-2, but with 2 minutes to play, it was still Reading's game. But, an 89th minute goal and a goal in the 5th minute of injury time took it to extra time. Arsenal then led 5-4, Reading equalised with 4 minutes to go, but then another last minute Arsenal double sent them through. When Reading manager Brian McDermott was asked if he'd watch the DVD of this extraordinary match, he replied "No, I'll probably throw it in the bin."
Motherwell 6-6 Hibernian (2010)
Needless to say than any game featuring 12 goals is likely to be a belter, but this one was special even within that rarefied species, with Motherwell recovering from 6-2 down after 65 minutes to draw, with the final equaliser coming in the third minute of injury time. They even missed a penalty at 6-5. Sloppy.
Liverpool 3-3 AC Milan (2005)
A truly legendary comeback on the biggest club stage of all - the 2005 Champions' League Final. The first half saw Liverpool go 3 goals down and - more than that - utterly outclassed. In reality, it could have been 4 or 5, and Milan seemed psychologically sure of the win. Inevitably, some Liverpool fans also were, with some leaving the stadium at half-time - but they should have had more faith as goals from Gerrard, Smicer and Alonso levelled the match up, taking it to extra time and then penalties. Jerzy Dudek brought out the Grobbelaaar wobble legs, saved from Pirlo and Shevchenko and Liverpool had claimed an utterly remarkable victory, dubbed the 'Miracle of Istanbul'.
Newcastle 4-4 Arsenal (2011)
4-0 down at half time, Newcastle stood humiliated in their own St James' Park stadium, yet the sending-off of Abou Diaby just after the break gave the magpies a glimmer of hope. And how well they took that chance, with a barrage of 4 goals in 19 minutes levelling things up in one of the all-time great Premier League combacks - the last of them a stunning long-range thunderbolt from Cheik Tiote with 3 minutes remaining which prompted wild celebrations amongst the massed Geordies.
Blackpool 4-3 Bolton Wanderers
The most famous FA Cup final of all, this was a classic match which went down in history, known as the Matthews Final. Bolton led 3-1 at Wembley in front of over 100,000 fans with 20 minutes to play before Stanley Matthews crossed for Stan Mortensen to score his second of the game to make it 3-2. He completed his hat-trick - still the only one in an FA Cup Final - via a free kick to level things up with a minute remaining, before another Matthews cross in the second minute of injury time was met by Bill Parry to seal a famous win. Legend has it that Bolton's Nat Lofthouse stood and applauded after the final goal, while Matthews himself credited the team and especially Mortensen for the victory, never accepting the nickname of the 'Matthews Final'. Football really was better in the old days wasn't it?
Barcelona 1-4 Metz (1984)
A brilliant comeback - not only in pure footballing terms, but also because of the stories that unfolded around it. Metz lost the first leg of this Cup Winners' Cup (kids, ask your dad) match 4-2 at home and the French media was so convinced that it was au revoir for Metz - they'd also lost recent league games 6-0 and 7-0 - that no TV or radio station bothered to cover the return leg. The Spanish felt the same, with the Nou Camp just a quarter full and Barca midfielder Bernd Schuster saying that he would "give the Metz players some ham when they come to our place to thank them for the presents that they give us tonight". Well, pride comes before a fall and, after Barca opened the scoring to make it 5-2 on aggregate, Metz roared back, scoring 4 unanswered goals from the 38th minute onwards. When Tony Kurbos scored the 4th, and completed his hat-trick, Michel Ettore, the Metz goalkeeper, ran up to to Schuster and shouted "Where's your ham now?" He went on to say after the match, "I don't think he speaks French but he understood me that night."
Germany 4-4 Sweden (2012)
A modern classic, as the powerhouse that is the German national team threw away a four-goal lead for the first, and only, time in their history. The Germans had looked to be cruising as they led 4-0 in this World Cup qualifier with just 28 minutes remaining. However, they hadn't reckoned on the plucky Swedes, who pulled goals back through Ibrahimovic, Lustig and Elmander, before Rasmus Elm scored a stunning equaliser in injury time. The German manager Joachim Löw was in a "state of shock" at the final whistle, while the Swedes...well, the Swedes were very happy - as you can hear in the commentary on the video below (scroll to 8:00 for the equaliser).
Spurs 3-4 Manchester City (2004)
Being 3-0 down at half-time is bad enough. Being 3-0 down and also down to 10 men - well, there's hardly any point even coming out of the dressing room for the second half. But City fans will forever be glad that they did, as their team, marshalled by renowned involver-in-incredible-matches Kevin Keegan, staged an unbelievable comeback, scoring 4 goals to seal their place in the next round of the Cup. At half-time, Keegan apparently said to his coach Derek Fazackerley, "We're 3-0 down and a man down, where's the nearest job centre?" 45 minutes later they would be taking the acclaim of the City faithful. It's a funny old game.
Mali 4-4 Angola (2010)
Another frankly ridiculous comeback from 4 goals down, this one - in the African Cup of Nations in 2010 - was even more remarkable than the others, as all 4 goals for Mali came in the final 11 minutes of the match. As if that wasn't enough, it was the opening game of the tournament and Angola were the host nation - someone really should have told Mali that it's not a very polite thing to do to your hosts, embarrassing them like that in their own country.
Gillingham 2-2 Manchester City (1999)
One of the most exciting matches in football history, this was arguably the moment that changed the course of Manchester City's history forever. The score, in the Division Two play-off final, was 0-0 with 9 minutes to go when Carl Asaba scored for Gillingham and, when Robert Taylor added a second 5 minutes later, it looked like City were doomed to spend another season in the third tier of English football. Many City fans left Wembley and, legend has it, stopped halfway down Wembley Way when they heard a first roar go up - Kevin Horlock pulling one back in the 90th minute - then started running back into the stadium when they heard a second roar - Paul Dickov smashing in another in the fifth minute of injury time, taking the game to extra time. With no further goals, City then triumphed in a penalty shoot-out and won promotion - they never looked back.