He crossed his arms for the first time and showed the symbol of the two hammers to a sold out London Stadium, a dream come true. On that day, February 1st, Soucek announced himself to the Premier League.
Moments later, he sat in the stands and watched as West Ham fell short of a dominant Liverpool team. Two days later, the Czech midfielder was included in the Hammers' starting XI against Brighton.
David Moyes understood very quickly that without his reinforcement from Slavia Prague, wearing the number 28 in the middle of the pitch, West Ham were worse off - and the fans knew it too.
Whether Julen Lopetegui or current manager Graham Potter (incidentally the coach against whom Soucek made his Premier League debut against) is on the bench, Soucek's position hasn't changed. On the contrary, his status has only gained in strength.
The midfielder grew into a mainstay for West Ham and the team's chances of picking up points varied greatly depending on whether Soucek was playing or not. These are not assumptions, but hard facts.
Since making his debut in 2020, he has played 183 Premier League matches - starting 171 times. And that's quite a lot, at least from a Czech perspective; only Petr Cech (443) and Patrik Berger (229) have played more games in the English top flight. And in terms of goals, he's only six behind Berger.
Soucek can now be described as West Ham's 'Iron Man', as he has played at least 32 league games out of a possible 38 in every season since making his debut.
Excluding goalkeepers, only James Tarkowski (187) and Bruno Fernandes (184) have played more matches since Soucek's debut.
Why? The West Ham coaches' decision is backed up by data from Opta, which may help with an answer. With the Czech midfielder in the line-up, the east London team has simply performed better - scoring more goals and conceding fewer on average. The same also goes for shots for and shots against.
It is also reflected in the club's successes; the Hammers have enjoyed a 10% higher success rate with the Czech captain in the team and the average points per game has been half a point higher than whenever the midfielder has been absent.
However, he has also performed well on an individual level. During his time in England, only Jordan Ayew (2,449) has made more tackles in the Premier League. Soucek has made 2,320 - and in terms of duels won, only the aforementioned Tarkowski (1,224) has had a better success rate (1,237).
However, where the Czech star really stands out is in headed duels - he has had 1,314 of them, while the second-best, Chris Wood, has 1,269. As far as the success rate is concerned, only Tarkowski again is better (774 compared to Soucek's 737).
Soucek, additionally, ranks fourth in ground interceptions, behind Jan Bednark, former teammate Declan Rice and - once more - Tarkowski during his time in the Premier League.
Furthermore, Soucek has made a crucial contribution where few would expect him to - in scoring goals. That said, no fewer than 28 of the 32 goals he's scored have either put West Ham into the lead or pulled them level.
If we take players who have scored at least 15 goals for the club and compare them, Soucek's 87.5% rate is the second-best figure after Bobby Zamora. He leads, for example, former attacking stars Joe Cole, Andy Carroll and Javier Hernandez.
Additionally, if he manages to score a winning goal again in the near future, he will surpass Kevin Nolan for second in the club's historical ranks - thanks to a greater percentage (he now has 12 match-winning goals out of his 32: 37.5%). First in this regard is Chelsea legend and former Hammer Frank Lampard, who scored 10 match-winners out of 24 goals for the club (41.7%).
When could Soucek overtake him? He'll only need four goals to do it, but watch out! Jarrod Bowen is catching up; the Englishman has 17 match-winners in his 50 goals (34%).
That said, Soucek's record in the Premier League is incredible for a defensive midfielder. Today, the 30-year-old can give himself a gift in West Ham's clash with Leicester - an opponent who has has not yet scored against in the league.