Luis Diaz was Liverpool's game-changer on Tuesday evening.
At half-time in their Champions League semi-final second leg against Villarreal, the Reds were 2-0 down and the tie was level on aggregate.
Unai Emery's side were magnificent in the opening 45 minutes on home soil, with Boulaye Dia and ex-Arsenal man Francis Coquelin grabbing the goals.
But in the second half, Liverpool were a completely different animal and much of that was down to the introduction of Diaz.
The Colombian star replaced Diogo Jota at the interval and Villarreal just could not deal with him.
Diaz scored Liverpool's second goal, with Jurgen Klopp's outfit going on to win the match at the Estadio de la Cerámica 3-2.
The Reds have now booked their place in Paris for the 2021/22 Champions League final as they pursue an unprecedented quadruple.
VILLARREAL, SPAIN - MAY 03: Luis Diaz of Liverpool celebrates during the UEFA Champions League Semi Final Leg Two match between Villarreal and Liverpool at Estadio de la Ceramica on May 03, 2022 in Villarreal, Spain. (Photo by Eric Alonso/Getty Images)
Without the signing of Diaz from FC Porto in January, it's highly unlikely that Liverpool would still be in the mix to win all four major trophies.
He's added a new dimension to the attack and has also allowed Klopp to rotate his forward line very effectively.
And as well as dazzling on the pitch, Diaz has proven himself to be something of a footballing machine in 2021/22.
That's because no footballer has played more official games for club and country than him this season, according to Transfermarkt.
VILLARREAL, SPAIN - MAY 03: Luis Diaz of Liverpool runs with the ball during the UEFA Champions League Semi Final Leg Two match between Villarreal and Liverpool at Estadio de la Ceramica on May 03, 2022 in Villarreal, Spain. (Photo by Eric Alonso/Getty Images)
Mohamed Salah and Sadio Mane aren't far behind their teammate, though...
The 20 footballers who've played the most official games in 2021/22
20. Brennan Johnson (Nottingham Forest & Wales) - 56 matches
19. Harry Kane (Tottenham Hotspur & England) - 57 matches
18. Callum McGregor (Celtic & Scotland) - 57 matches
17. Tomas Soucek (West Ham & Czech Republic) - 57 matches
16. Rodrigo De Paul (Atletico Madrid & Argentina) - 57 matches
15. Stheven Robles (Comunicaciones & Guatemala) - 57 matches
14. Sam Smith (Cambridge United) - 57 matches
13. Kerem Akturkoglu (Galatasaray & Turkey) - 58 matches
12. Jonathan David (Lille & Canada) - 58 matches
11. Liel Abada (Celtic & Israel) - 58 matches
GLASGOW, SCOTLAND - APRIL 09: Daizen Maeda of Celtic celebrates after setting up Liel Abada who scored the seventh goal during the Cinch Scottish Premiership match between Celtic FC and St. Johnstone FC at Celtic Park on April 09, 2022 in Glasgow, Scotland. (Photo by Ian MacNicol/Getty Images)
10. Kasper Schmeichel (Leicester & Denmark) - 59 matches
9. Jordan Henderson (Liverpool & England) - 59 matches
8. Chiedozie Ogbene (Rotherham & Republic of Ireland) - 59 matches
7. Andreas Hanche-Olsen (Gent & Norway) - 59 matches
6. Mason Mount (Chelsea & England) - 59 matches
5. Michael Ngadeu (Gent & Cameroon) - 60 matches
4. Sadio Mane (Liverpool & Senegal) - 60 matches
3. Mohamed Salah (Liverpool & Egypt) - 60 matches
2. Joe Aribo (Rangers & Nigeria) - 63 matches
- Luis Diaz (Liverpool, FC Porto & Colombia) - 64 matches
VILLARREAL, SPAIN - MAY 03: Luis Diaz of Liverpool celebrates after scoring their team's second goal during the UEFA Champions League Semi Final Leg Two match between Villarreal and Liverpool at Estadio de la Ceramica on May 03, 2022 in Villarreal, Spain. (Photo by Eric Alonso/Getty Images)
That is some effort from Diaz.
It's even more impressive when you remember that he's had to travel between Europe and South America for every international break this season, which is very time-consuming.
The signing of Diaz really was a masterstroke by Liverpool.