But who exactly is the Dutch attacking midfielder nicknamed "cheese straw" due to his slight build and bright blonde hair? bundesliga.com has the essentials…
1) 42-second impact
Born in the city of Hilversum, approximately 20 miles south of the Dutch capital of Amsterdam, Klaassen started playing football at the age of four and was recruited into the Ajax academy when he was 11.
Just seven years later, after working his way up through the ranks and representing the Netherlands at youth level, he made his senior debut for the club in a 0-0 draw against Olympique Lyon in the UEFA Champions League on 22 November 2011. A week later he made his Eredivisie bow, coming on as an 81st-minute substitute against NEC and scoring just 42 seconds later to round out a 3-0 win.
2) Slow burner
As auspicious a start as that was, it did not immediately pave the way for Klaassen to break into the first team. Although the attacker - who grew up idolising his compatriot Dennis Bergkamp - earned Eredivisie winners' medals in 2012 and 2013, it was not until the following year that he would truly make his mark on a regular basis.
Klaassen exploded onto the scene in 2013/14, scoring 12 goals and providing four assists across all competitions as Ajax once again lifted the league title. He proved he was no one-hit wonder the following season with eight more goals and a further 12 assists, incidentally playing alongside future Bremen team-mate Niklas Moisander. Such was his influence on the team by that point that he was made Ajax captain at start of 2015/16 and he repaid the club's faith in him with another barnstorming year that ended with him being voted Dutch Player of the Year by his fellow professionals in 2016.
3) Schalke menace, Europa League runner-up
By this stage, Klaassen was already a full Dutch international, having been handed his maiden cap by former Bayern Munich coach Louis van Gaal in November 2014. He proved he was comfortable on the international stage in 2016/17, captaining Ajax under Peter Bosz – who would later go on to become Borussia Dortmund coach – all the way to the UEFA Europa League final, even scoring a brace against Schalke in the first leg of the quarter-finals.
That was enough to convince Everton to pounce in summer 2017, with then coach Ronald Koeman full of praise for his countryman: "He's hardworking, likes to press and, of course, will give us more creativity and goals." However, the Toffees changed manager three times in 2017/18, which was hardly helpful for a player trying to find his feet in a new country. After making just seven Premier League appearances last season and another change of coach in May 2018, Klaassen decided enough was enough and opted to joined Bremen.
4) Cruyff: "Klaassen is like Xavi and Kroos"
The ultimate seal of approval for any Dutch player – or a footballer of any nationality for that matter – was an endorsement by the legendary Johann Cruyff. The former Ajax and Barcelona star, who passed away in 2016, did not give out praise to just anyone, though, meaning his admiration of Klaassen should not be taken lightly.
“You must have strong positioning, ability to control the ball at speed and also have the technique to deal with the speed of it [in midfield]," said Cruyff in an interview with Voetball International 2014.
"Xavi, Toni Kroos and Davy Klaassen can do it. All three have perfect anticipation and they can play it both left and right excellently. You watch, when Klaassen plays from that position for Ajax, the tempo increases immediately. Moreover, he rarely loses possession."
5) Footballing family
Perhaps Klaassen was always destined to be a footballer, as his father Gert-Jan used to be a goalkeeper. "That's my first memory in football," Klaassen recalled. "I went along to watch a game with my mum and saw him save a penalty. I thought: 'this man is the best goalkeeper in the world'." His younger brother Aron also a footballer, plying his trade at Dutch lower-league side SV Huizen.
So what can Bremen expect of their latest recruit? “I’m an attacking midfielder player who likes to get in the box. I also like to be aggressive on the field and press all the time. I like to score and create goals and I like to win."