Mohamed Salah, Kevin De Bruyne and Romelu Lukaku - the ones that got away for Chelsea.
They've been in phenomenal form for Liverpool, Manchester City and Manchester United respectively this season, forcing their former employers to regret their sales.
Salah joined from Basel for £11 million in 2014 but, following loan spells at Fiorentina and AS Roma, departed two years later.
He's now at Liverpool and enjoying the best season of his career, scoring 20 goals and making four assists in his opening 25 games for the Reds.
Meanwhile, De Bruyne has established himself as arguably the Premier League's finest by firing City to the top of the table with some mesmerising performances.
Chelsea signed the Belgian as a 20-year-old in 2012 and then shipped him to Wolfsburg in 2014 for a meagre £18 million. He's now worth five times that.
And then there's Lukaku, who spent three years at Stamford Bridge but wasn't given enough opportunities to prove his worth.
Jose Mourinho sold the striker to Everton in 2014 and he's since completed a £75 million summer move to United, where he's scored 14 goals in all competitions.
So safe to say Chelsea have made some transfer blunders over the past three years, but John Terry has no regrets about their departures.
Speaking on Monday Night Football after Everton 3-1 Swansea City, Terry perfectly explained why they should have no shame about selling Salah, De Bruyne and Lukaku as exciting youngsters.
Asked if he regretted them leaving, the centre-back said: "Not really, because at the time they didn't make our team stronger.
"Let's not forget we were one of the best teams probably the Premier League has ever seen, in them early days when they arrived.
"So they was coming into one of the best sides. When they come in, can they make a big enough impact to sustain and keep their place? No, it's very difficult to do."
Can't argue with that. Salah (2016), De Bruyne (2014) and Lukaku (2014) were all sold in summer transfer windows leading up to title-winning campaigns, so at the time it made sense.
In 2014, for example, De Bruyne and Lukaku were competing against the likes of Didier Drogba, Diego Costa, Eden Hazard, Willian, Oscar and Cesc Fabregas for places.
In hindsight, it's no wonder the trio were sold, so Terry's explanation will go some way towards easing the pain Chelsea fans have felt so far this season.