Enzo Fernandez was booed by some supporters on the day when Morgan Rogers scored on his first appearance for Chelsea in a 3-1 win against Real Sociedad.
Joao Pedro also continued his fine pre-season form with a double as manager Xabi Alonso offered a glimpse of what could be his blueprint for the season.
But the action was overshadowed by the reaction to Fernandez's second-half appearance, less than 24 hours after Chelsea's self-imposed transfer deadline had passed.
Fernandez had been keen to join Real Madrid earlier this summer before the Spanish club ended their interest in the Argentine.
His representatives later held talks with Manchester City, but no offer was made to meet Chelsea's £120m valuation before Friday's 17:00 BST deadline.
Fernandez was booed by some early arrivals at Stamford Bridge when his name was read out 45 minutes before kick-off.
There were then audible boos when Fernandez came on in the 62nd minute.
Chelsea supporters appeared divided, with others responding by chanting his name.
Yet, it was a signal of Alonso and Chelsea's backing that when Reece James left the field he passed his long-time vice-captain the armband as usual.
Each touch of the ball was greeted by a mixture of boos and cheers.
It followed attempts by some supporters to move on from a saga that appears to have ended with Chelsea now expecting to keep one of their best players.
Others, however, remain unhappy with his perceived disloyalty, having come out publicly about his desire to move to Madrid, with his agent Javier Pastore also claiming he is underpaid.
It will be interesting to see how supporters of the Premier League's other 19 clubs react to Fernandez, given his celebrations and social media jibes after Argentina beat England in a World Cup semi-final in July.
That will remain an issue whether he remains at Chelsea or Manchester City elect to revive their interest and attempt to reunite him with his former manager Enzo Maresca before deadline day on 1 September.
It took Rogers only seven minutes to score his first goal in a Chelsea shirt as he reacted quickest after Alex Remiro saved Joao Pedro's initial header.
The £117m club record signing from Aston Villa initially looked sharp and linked well with Cole Palmer and Pedro in Chelsea's front three.
Within 10 minutes of his debut, supporters were already chanting his name.
However, it was understandable that Rogers faded as the match wore on, given he had trained for less than a week since returning from holiday before his 62-minute outing.
Beyond Rogers, Joao Pedro has been the star of Chelsea's pre-season.
In this outing he headed Chelsea back in front in the 47th minute before adding a side-footed finish 30 minutes later to seal victory after Sociedad had equalised just before half-time through Jon Mikel Aramburu's volley.
Chelsea lost control towards the end of the first half and looked vulnerable, but they were much improved after the break.
Joao Pedro has scored eight goals in seven pre-season matches and led the line with Rogers and Palmer operating behind him.
Alonso offered a glimpse of the 3-4-2-1 formation he could use at Fulham in Chelsea's Premier League opener as he took charge of a match at Stamford Bridge for the first time.
It featured Robert Sanchez as the first-choice goalkeeper, with Wesley Fofana, new signing Maxence Lacroix and Levi Colwill forming a back three - from right to left.
Pedro Neto operated at right wing-back and Marco Palestra on the left, while captain Reece James and Moises Caicedo lined up in midfield behind the front three.
There was also a debut from substitute wing-back Pep Chavarria, although a number of notable players were absent.
Of course, Alonso insists he won't be wedded to either a back three or four but it was this system used as Chelsea beat AC Milan 3-0 a week ago.
