After the £97.5m signing of Romelu Lukaku and their battling performance against Liverpool at Anfield prior to the international break, European champions Chelsea further enhanced their title credentials with the Deadline Day signing of Saul Niguez.
"Just another excellent player," is how Gary Neville described him in the wake of his arrival from Atletico Madrid. Saul, whose season-long loan deal contains a £30m option to buy next summer, brings "massive experience" to a squad already full of it.
"He fits the Chelsea profile of signing players who are ready," added the Sky Sports pundit.
Saul's pedigree is indisputable. At 26, he arrives at Stamford Bridge having already amassed 340 appearances for Atletico and won 19 caps for Spain. The "massive experience" Neville mentioned includes trophy wins both domestically and in Europe.
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The most recent came just a few months ago, when he helped Atletico claim La Liga glory, but it was time for a change.
Diego Simeone once said Saul had "all the qualities to be one of the world's best midfielders" but his standing had slipped at the Wanda Metropolitano Stadium in recent years.
In his introductory interview as a Chelsea player, Saul described himself as a "team player" first and foremost. His selflessness is an admirable trait but it has not always helped him on a personal level.
He broke into the Atletico team as an all-action central midfielder during the 2014/15 campaign and went on to keep his place there for several seasons. But even before that, he had demonstrated an ability - and willingness - to play in different positions.
Indeed, during the 2013/14 season on loan with Rayo Vallecano, his first at La Liga level, he split his time between midfield and central defence. Over the years back at Atletico, he began to be used everywhere from left-back to right wing.
His versatility was an undoubted asset to Simeone but it prevented Saul from flourishing in his favoured role.
Instead, he was moved around to accommodate others.
Last season, he found himself behind his former academy team-mate Koke, Marcos Llorente and even the previously out-of-favour Thomas Lemar in the midfield pecking order.
The subsequent arrival of Rodrigo de Paul for £30m from Udinese further increased the competition for places in Simeone's midfield.
Saul did start their first two La Liga games of the season, against Celta Vigo and Elche, but both times at left wing-back.
In typically selfless style, Saul did what was asked of him with total dedication in those games, even providing the assist for Angel Correa's decisive goal in the 2-1 win over Celta.
Now, though, he hopes to return to a central position at Chelsea. Leaving Atletico was "hard", he added last week, "but it was a great opportunity for me and for my career and I had to take the chance."
'An excellent signing for Chelsea'
Spanish football expert Terry Gibson:
“I wouldn’t say his form has suffered in recent years, but his reputation has, because he’s been playing here, there and everywhere, which has seen him left out of the Spain squad.
“I’ve always thought at the age of 26, he should be nailed on to be in that squad. But if Chelsea use him in midfield, which I expect them to do, I still feel the best is yet to come.
“He’s dynamic, he gets forward, he can score goals, he puts his foot in, he works hard. He has all the traits you need to play for Simeone and I think he’s an excellent signing for Chelsea.
“I genuinely feel he is as good as it comes in central midfield. I’m surprised the signing took so long because as soon as he was available, and he has been throughout the summer, I thought someone would go and snap him up straight away.”
Saul went into more detail about the move to Chelsea in a separate interview with Ibai Llanos, a popular eSports personality in Spain. In it, he revealed Thomas Tuchel had offered him reassurance that he intends to use him in midfield.
"That is the most important reason for my decision," said Saul. "The three midfielders who are playing are at a high level and it will not be easy to start, but if I put my mind to it and fight it, I can do it."
Jorginho, N'Golo Kante and Mateo Kovacic all bring different qualities to Tuchel's midfield.
Jorginho is a metronomic passer who dictates the play and orchestrates attacks; Kante is a tireless runner who offers outstanding defensive coverage; Kovacic is a powerful ball-carrier who excels in one-on-one situations.
Saul, though, offers a bit of everything. Sergio Busquets, who has partnered him in Spain's midfield on numerous occasions at international level, describes him as a "very complete player". Luis Enrique, Spain's manager, has used the same term.
Neville, meanwhile, expects him to strengthen Chelsea "enormously". "In midfield, with Jorginho, N'Golo Kante and Mateo Kovacic, they already look really strong," he said.
"The addition of Saul makes the stronger and stronger. You only need two in there with the way they play, but Saul's addition means they can challenge on all fronts."
Saul describes himself as a "box-to-box midfielder" who likes "joining the attack and scoring goals" but Tuchel will value his defensive qualities just as highly as his attacking ones.
Playing under Simeone demands a willingness to "suffer" out of possession and Saul excels in that regard. He is tactically intelligent and defensively diligent. Even last season, he averaged more tackles per 90 minutes (2.5) than any other Atletico player.
Saul has a history of impressing in big games too. One of his first goals for Atletico was a stunning overhead kick in a 4-0 thrashing of bitter rivals Real Madrid in 2015. He was only 20 at the time but soon developed a habit of shining in the Champions League too.
When Atletico famously overcame Liverpool in the last-16 stage of the competition in 2020, Saul scored the winner in the first leg - becoming only the second Atletico player to reach 10 Champions League goals after Antoine Griezmann - before producing an outstanding defensive display in the second, winning 10 of his 11 aerial duels at Anfield and highlighting another of his best attributes.
Indeed, Saul's aerial ability is just another factor behind Tuchel's decision to take him to Stamford Bridge - and it is just another area in which he will strengthen them. Chelsea's title credentials already looked compelling. Now even more so.
Premier League Preview: Souness on Leeds vs Liverpool | Ronaldo's return | Chelsea's title hopes
Sky Sports pundit Graeme Souness joins the Essential Football Podcast as Alice Piper, Peter Smith and Richard Morgan discuss the big talking points ahead of the Premier League weekend.
PART 1 | Souness' verdict on Leeds vs Liverpool, Virgil van Dijk's comeback, and Elland Road memories
PART 2 | Chelsea's title chances, what Saul Niguez brings to the team, and how international issues will affect Chelsea and Aston Villa
PART 3 | What can we expect from Cristiano Ronaldo's return to Manchester United? And is Gareth Southgate's first choice England XI now set in stone?
Watch Chelsea vs Aston Villa live on Sky Sports Premier League from 5pm on Saturday; kick-off 5.30pm