Red Bull's plans for the 2019 Formula One season were hampered on Friday as Daniel Ricciardo confirmed a switch to Renault.
Ricciardo's future had long been the source of speculation, but it had appeared as though he would be renewing his Red Bull deal rather than moving on.
The Austrian outfit must now identify a replacement to feature under star youngster Max Verstappen, whose considerable shadow may well have impacted Ricciardo's decision.
Red Bull team principal Christian Horner said in a statement: "We will now continue to evaluate the numerous options available to us before deciding on which driver partners Max Verstappen for the 2019 season."
With rumours of interest in various drivers sure to follow, we have assessed the potential candidates.
CARLOS SAINZ JR
With Ricciardo joining Renault, Carlos Sainz Jr - on loan with the French team - will be on the move come the end of the season. Already contracted to Red Bull, he is the obvious option to replace Ricciardo in what would be a straight switch.
Horner and Co. will no doubt have kept a close eye on Sainz this year as speculation surrounding Ricciardo wore on, and he can only have been impressed by the Spaniard's steady displays.
Sainz has completed all but one race, finishing no lower than 12th all season. At 23, he has time on his side, too.
While Sainz is the obvious option, Horner's statement did say that Red Bull would be considering all of their various options. However, even if they were to look elsewhere, Pierre Gasly offers a familiar face.
A star with sister team Toro Rosso, Gasly previously served as Red Bull's test driver.
The Frenchman is just 22 years old but has already been mixing it with the big boys in his first full F1 season, finishing fourth in Bahrain, and Red Bull would have a youthful line-up full of promise with Gasly alongside Verstappen.
An incredible swoop for Lewis Hamilton, Valtteri Bottas or Sebastian Vettel seems highly unlikely, but there are other drivers whose futures are not quite so secure.
Ferrari appear set to make a move for Charles Leclerc, with the suggestion being that Kimi Raikkonen would retire, yet Red Bull must surely consider competing for the Monegasque driver. And if that deal is done, Raikkonen has shown himself capable of still competing in F1 this season. A bid for the Finn would be huge surprise but his presence would give Verstappen a famously laid back mentor.
|Emery: Arsenal must be calm with returning Koscielny|
|Sevilla don´t fear Messi or Barca – Kjaer|
|Conte, Zidane and the AC Milan contenders clouding Gattuso´s future|
|Koepka in control in South Korea, on track to become world number one|
|Dovizioso grabs pole at Motegi, Marquez sixth|
|Langer backs Marsh for ODI squad|
|Butler turns boos to MVP chants in Timberwolves´ first win|
|Brewers force game seven against Dodgers in NLCS|
|Guardiola admits Hart decision may have been a mistake|
|Vieira: Balotelli the same now as he was at 16|
|Butragueno backs under-fire Lopetegui|
|Liverpool´s defensive improvement has hurt attack – Klopp|
|Butler booed by Timberwolves fans during introductions|
|Pochettino: Dier´s Ramos tackle highlighted Spurs´ attitude|
|Man City working on new deal for Sane – Guardiola|
|Golden Knights sign RW Tuch to seven-year extension|
|Bryant explains how Lakers could beat Warriors|
|Finals hopefuls Isner, Fognini into Stockholm semis|
|Browns trade running back Hyde to Jaguars|
|Mourinho: I´d love to have Hazard at Manchester United|
|Hamilton´s title chances enhanced by Vettel´s grid penalty|
|Deja vu for Enisei as La Rochelle inflict another thrashing|
|Five-star Jovic makes Bundesliga history|
|Liverpool´s scoring slump no concern for cautious Klopp|
|He´s the Special One - Sarri insists he is not on Mourinho´s level yet|
|Second-half blitz guides Leicester to European success|
|Sheffield Wednesday 1 Middlesbrough 2: Besic, Assombalonga see off Owls|
|Goerges rallies to reach Luxembourg Open final, Jabeur makes history|
|Howe: Transfer speculation will not disrupt Ake|
|´Do we really want opera every night?´ - Klopp not changing Nations League view|
|Vile and abhorrent – Chelsea´s Carney responds to online abuse|
|Giants WR Beckham Jr. explains why he might cramp up: ´I really don´t like water´|
|Man City pay training-pitch tribute to Joe Hart|
|Neymar to be rested as Tuchel rubbishes Ballon d´Or concerns|
|Sarri ´not interested´ in Christensen father´s quit threat|
|Cardinals fire offensive coordinator McCoy after 1-6 start|
|Neymar return unlikely, but anything can happen – Valverde|
|Bairstow a doubt for fourth ODI|
|Manchester United fined for late arrival and delayed kick-off against Valencia|
|Australia-Pakistan chat not ´especially polite´ - Sarfraz|
|Pogba relishing ´pressure game´ against in-form Hazard|
|Don´t bet on Cardiff survival, warns Warnock|
|Buffon enjoying Tuchel´s methods at PSG|
|RIP to Wimbledon epics! Isner feels like The Undertaker following final-set tie-break rule|
|Sevilla performance sealed Bernat´s Bayern exit - Hoeness|
|Keita set to miss out as Liverpool monitor injured stars|
|He didn´t want to be here – Guardiola doubts Sancho will return to Manchester City|
|Sarri: Manchester United are the best in the Premier League|
|Mourinho salutes ´brave´ Shaw for ´best possible´ response to criticism|
|No Ballon d´Or distractions for Griezmann, insists Simeone|
|Wigan stand by Hardaker as full-back prepares to undergo rehabilitation|
|Barcelona deny Neymar talk|
|Hazard can win the Ballon d´Or as a Chelsea player, insists Sarri|
|De Bruyne in contention to start in Manchester City´s clash with Burnley|
|Neymar needs to mature to reach Messi levels - Xavi|
|We have a hell of a lot to do - Paine slams Australia batting|
|Kerber and Osaka to meet at WTA Finals|
|Lorenzo out of Japanese MotoGP|
|Real Madrid handed Africa trip in Copa del Rey|
|Allegri: Ronaldo has sharpened Juventus focus|
|No Wade in Wasps squad amid NFL reports|
|Rooney: Five of us controlled Man United dressing room|
|Bayern bosses launch scathing attack on ´disrespectful´ media|
|Saints lock in Lawes to new deal|
|Adelaide United 1 Sydney 1: Debutant Le Fondre rescues a point|
|Madrid can´t look back, only forward - Lopetegui confident of revival|
|Wimbledon to introduce final-set tie-breaks|
|Abbas inspires Pakistan to series victory|
|Madrid boss Lopetegui hopeful on Bale availability|
|Mood is positive at Bayern, insists under-pressure Kovac|