Manchester City and Chelsea have already played each other three times this season, but the Premier League rivals will finish the 2020-21 campaign with one last bout in Saturday's Champions League final.
City and Chelsea have never met in the Champions League before, but this is not their first ever European encounter. They came up against each other in the semifinals of the 1970-71 UEFA European Cup Winners' Cup, with the Blues winning both legs 1-0 to reach the final, which they also won by beating Real Madrid in a replay.
Chelsea are also narrowly leading in head-to-head terms on the domestic front too, having won 68 of the 166 competitive games they've played against City, who have claimed 58 victories since their first-ever meeting in 1907.
This season, City steamed to a 3-1 victory at Stamford Bridge in the league in early January before falling to a 1-0 defeat against the Blues in the FA Cup semifinals last month. The last time the two teams met prior to this weekend's final in Porto was on May 8, when a 92nd-minute winner from Marcos Alonso saw Thomas Tuchel's side flee the Etihad with a 2-1 victory.
There was a time when finals between two clubs from the same country were a rare occurrence, but they've become something of the norm in recent years. Overall, there have been seven Champions League finals that have pitted two domestic rivals against one another -- the first coming in 1999-00 when teams from the Spanish top-flight dominated the latter stages.
Five of the last nine finals have been contested by two rival sides from the same league, so perhaps we should get used to these Champions League "derbies."
Real Madrid vs Valencia (1999-00)
Although the old European Cup was rebranded as the Champions League in 1992, it was not until four years later that two teams from the same country appeared in the group stage when AC Milan and Juventus both represented Italy.
Just three seasons later, the first intra-national Champions League final was played at the Stade de France in Paris. The latter stages of the tournament were dominated by Spanish sides, with three of the four semifinalists hailing from La Liga -- Real, Valencia, and Barcelona -- alongside Bayern Munich.
It was Real and Valencia who made it through to the grand finale, with the former easing to a comfortable 3-0 win to claim their second European title in three years and a then-record eighth overall. The goals came from Fernando Morientes, Raul Gonzalez and, most spectacularly of all, Steve McManaman -- who became the first ever English player to win the competition with a non-English team.
AC Milan vs. Juventus (2002-03)
A drab final that doesn't linger long in the memories of most fans, the two Italian clubs toiled for 120 goalless minutes at Old Trafford before the tie was finally settled on penalties. The 2003 final is one of just four European Cup finals to end 0-0 after regulation time from all 65 that have been played since the first in 1955-56.
Even the shootout was fairly underwhelming, with five of the first nine penalties missed before Andriy Shevchenko (who had a goal disallowed in the first half) held his nerve to grab the glory for the Rossoneri as sudden death loomed.
Manchester United vs. Chelsea (2007-08)
On a freezing, rain-lashed night in Moscow, Manchester United ultimately held out to win a long and gruelling first all-English Champions League final. Cristiano Ronaldo's first-half opener was cancelled out by Frank Lampard on the stroke of half-time. Chelsea rattled United's woodwork twice, but there were no more goals in the ensuing 75 minutes of play.
Penalties were ushered in and, after Petr Cech saved Ronaldo's stuttering shot, the Blues' battle-worn captain John Terry was afforded the chance to claim glory with his side's fifth penalty. Unfortunately, the sodden turf gave way beneath Terry's feet as his bungled spot-kick hit the post, leaving the skipper to watch on through tear-stained eyes as Edwin van der Sar produced the decisive save from Nicolas Anelka's sudden-death attempt to seal United's third European triumph.
Bayern Munich vs. Borussia Dortmund (2012-13)
After losing out to Chelsea in their own Allianz Arena the previous year, Bayern returned to the final in 2013 where they came up against Bundesliga foes Dortmund at Wembley. It was the Bavarians who emerged victorious in the competition's first ever all-German final, though they left it until the very last minute to beat Jurgen Klopp's side.
After Ilkay Gundogan's 68th-minute penalty had cancelled out Mario Mandzukic's opener on the hour mark, it was left to Arjen Robben to cap his sublime man-of-the-match performance by scoring the winning goal for Bayern in the 89th minute. His face was a picture of shocked delight.
Real Madrid vs. Atletico Madrid (2013-14)
The first time in history that both Champions League finalists were from the very same city, the 2014 showpiece saw Madrid rivals Real and Atletico come face-to-face over the border in Portugal. Real were actually trailing to a Diego Godin goal for the majority of the match, only for captain Sergio Ramos to pull a headed equaliser out of the ether in the 93rd minute and send the final to extra time.
Real Madrid vs. Atletico Madrid (2015-16)
Two years on from their barn-burner in Lisbon, warring neighbours Real and Atletico reconvened at the San Siro in Milan to have at it once again. The 2016 final was a much more sedate offering in comparison, finishing 1-1 after extra time before Real seized the trophy once again, this time on penalties.
Los Blancos were flawless in the shootout and when Juanfran hit the post with Atletico's fourth penalty, it was left to Ronaldo to wrap things up in emphatic fashion -- exorcising the ghost of his miss in 2008 in the process.
Liverpool vs Tottenham Hotspur (2018-19)
The first Champions League final to feature a video assistant referee, the 2019 edition saw Liverpool and Spurs go head-to-head at Atletico's Wanda Metropolitano stadium in Madrid. The opening goal came while many fans were still finding their seats after Mohamed Salah was awarded a dubious penalty just 22 seconds into the game, following a VAR review.
The Egyptian duly converted from the spot with 1:48 seconds on the clock, the second fastest goal ever scored in a Champions League final (after Paolo Maldini's for AC Milan against Liverpool in 2005, which was scored 50 seconds into the game). Substitute Divock Origi added a second late on, following up on his incredible winner in the Reds' miraculous semifinal comeback against Barcelona.
After losing out to Real Madrid in the 2017-18 final, Liverpool made no mistakes this time as they thrust to a 2-0 victory and claimed their sixth European Cup.