The result itself carried some unusual historical weight: it was England's first 4-2 win at a World Cup since the 1966 final against West Germany, and their first victory in the competition against a side ranked inside FIFA's top 15 since beating Argentina in 2002.
It was also arguably the first proper test of Tuchel's tenure.
Croatia, ranked 11th, arrived as a familiar tournament force after reaching the last four - including a final - at each of the previous two World Cups, but were eventually overwhelmed by England's attacking quality after the interval.
Harry Kane was central to the result, scoring twice to move level with Gary Lineker on 10 World Cup goals for England. His first came from the penalty spot after Noni Madueke was fouled by Luka Modric, who noticeably struggled throughout the encounter before being substituted early in the second half.
Dominik Livakovic saved Kane's initial effort, but the penalty was ordered to be retaken after the goalkeeper moved early and Josko Gvardiol encroached in the area. Kane converted the second attempt before later heading in Declan Rice's corner to restore England's lead.
The goals strengthened the Munich man's already outstanding tournament record, making him only the second England player, after David Beckham, to score at three different World Cups, while his 17 goals across major tournaments place him behind only Cristiano Ronaldo, Miroslav Klose, and Gerd Muller among European players.
First-half issues
Yet England's first-half performance gave Tuchel plenty to address.
Croatia twice equalised before the break, first through Martin Baturina's powerful finish after Bellingham had lost possession, then through Petar Musa, who converted Ivan Perisic's knockdown with almost the final action of the half. England had led twice, but their defensive spacing and lack of aggression without the ball allowed Croatia to stay in the contest.
Tuchel acknowledged afterwards that England had struggled in the first 45 minutes.
"The first half was a bit complicated for us," he told ITV Sport. "It was a bit nervy. The decisions we took, we chose to go safe and go backwards. We struggled to find any rhythm and didn't have the confidence to go through the gaps."
The former Chelsea manager also pointed to England winning only 33% of their ground duels in the first half, compared with 73% in the second, describing the reaction after half-time as the aspect he most admired.
Big match Bellingham
Whatever Tuchel said during the break, it clearly worked. England played with greater intensity, pressed higher, and moved the ball forward more decisively from the get-go. Within two minutes of the restart, Jude Bellingham put them ahead for a third time, finishing from a tight angle after Elliot Anderson's well-weighted pass down the right.
The Real Madrid star - who many expected to be starting from the bench - later said England had been "nervous and cagey" in the first half, but felt the second showed "the team we want to be", praising the level of intensity without the ball and the impact of the substitutes.
England then produced their strongest spell of the match. Livakovic was forced into several saves, denying Rice, Nico O'Reilly, and Anthony Gordon, while O'Reilly headed wide from another Rice corner. At one stage early in the second half, England had nine shots, eight of them on target, in the space of 10 minutes.
Croatia still carried a threat, and Jordan Pickford had to save from Marco Pasalic after England were again opened up too easily. That moment underlined the main concern from the night: England's attacking depth looks formidable, but their defensive control remains a work in progress.
The decisive fourth goal came from three substitutes. Djed Spence found Bukayo Saka, who drove in from the right and squared for Marcus Rashford to finish low into the corner. It was a clear demonstration of England's strength from the bench and gave Tuchel the cushion his side's second-half dominance had deserved.
'A game of two halves'
Kane described the match as "a game of two halves" and credited Tuchel's half-time intervention.
"He gave us a speech at half-time and said if we lose, we lose in our way," the Three Lions captain said afterwards. "We went full gas, and they couldn't live with it." He added that England's greater aggression without the ball felt decisive, particularly against a Croatian midfield capable of creating uncertainty through Modric's vision and potential to dictate.
The win does not remove all doubts, given that England conceded twice in a first half in which Croatia did not need sustained pressure to hurt them, and stronger opponents will test those defensive gaps more ruthlessly.
Still, as an opening statement, this was still a substantial result: a win against high-level opposition, a record-equalling night for Kane, a decisive contribution from Bellingham, and clear evidence that England can change the tempo of a match when they play with greater conviction.
Tuchel will know there is work to do, but he will be pleased England were able to correct some of their flaws and finished with a victory that should carry more weight than a routine opening win.
