The Champions League takes centre stage again this week with a place in the final at stake.

Knockout ties always throw up a few surprises with plucky underdogs in the mix looking to raise eyebrows.

We take a look at five of the biggest shocks in Champions League history as the remaining sides aim to reach the Istanbul showpiece.

AC Milan vs Deportivo La Coruna (Quarter-finals, 2003-04)

AC Milan — boasting the likes of Kaka, Paolo Maldini, Andrea Pirlo and Cafu in their line-up — were shocked by Deportivo La Coruna, who became the first team ever to overcome a three-goal deficit in the Champions League knockout stages.

This result is even more eye-opening today as the Spanish outfit now play in the third tier domestically following their relegation from the second division in 2020.

Milan cruised to a 4-1 first leg victory at the San Siro after going 1-0 down thanks to a Kaka brace and goals from Pirlo and Andriy Shevchenko.

But in the most unlikely of potential comebacks, Deportivo stunned Carlo Ancelotti’s men after going 3-0 up at half-time before substitute Fran bagged the fourth to spark wild celebrations.

Barcelona vs Roma (Quarter-finals, 2017-18)

Lionel Messi and Co probably thought their place in the semi-finals was booked after they thumped Roma 4-1 in the first leg with the help of two own goals that gifted the Catalan side a 2-0 lead.

Edin Dzeko’s away goal proved to be pivotal in the outcome of this tie as Roma shocked the football world and comfortably won the second leg 3-0 to level things on aggregate.

Barcelona managed to brush this shock exit aside and went on to win the double that season, clinching LaLiga and Copa del Rey titles under Ernesto Valverde’s management.

Ajax vs Real Madrid (Last 16, 2018-19)

The 2018-19 Champions League campaign arguably provided the most entertainment of any season as Ajax, Liverpool and Tottenham all produced remarkable comebacks.

The Dutch giants took on the competition’s most successful side, Real Madrid, and lost the first leg at the Johan Cruyff Arena as Marco Asensio scored late on to give his side a narrow advantage.

Madrid losing on home soil with an advantage in the Champions League is usually unthinkable, particularly against underdogs and given their numerous recent successes in the competition.

However, Hakim Ziyech, who later secured a move to Chelsea off the back of his performances in red and white, propelled Ajax to a resounding 4-1 victory in the Spanish capital.

Monaco vs Real Madrid (Quarter-finals, 2003-04)

Another quarter-final from the 2003-04 season makes this list after Monaco stunned the Galacticos against all odds.

The Monegasques got off to a great start at the Bernabeu, taking a 1-0 lead into half-time before Madrid responded with four after the break.

Fernando Morientes, on loan from the Spanish side at the time, scored what turned out to be a vital away goal in the 84th minute to make it 4-2 on the night.

Madrid legend Raul had initially fired Madrid into the lead in the second leg before a Ludovic Giuly brace and another strike from Morientes helped send his parent club packing.

Monaco marched on to the semi-finals on away goals with an aggregate score of 5-5, sensationally completing the comeback in front of their own fans. 

Porto v Manchester United (Last 16, 2003-04)

Porto produced a historic campaign under Jose Mourinho as they won the Portuguese title and went on to clinch the Champions League trophy by beating Monaco 3-0 in the final.

The Portuguese outfit had already won two major trophies, including the UEFA Cup, under a young Mourinho the previous season.

Porto triumphed at home against giants Manchester United as Quinton Fortune’s opener for the visitors was cancelled out by a double from fellow South African Benni McCarthy, while Roy Keane was sent off late on.

Paul Scholes’ first-half header in the second leg seemed to be the goal that would send the Red Devils through to the Champions League quarter-finals for an eighth successive season.

But in late drama, a goalkeeping mistake at the death from Tim Howard gifted Costinha with a simple finish that left Old Trafford heartbroken.