If this bids true, which it seems it may be, then alongside Gueye is a must, this lads 20 and whilst a complete and utter unit is inexperienced and it shows watching his clips, he'd need someone alongside him with quality and experience to learn from - Gueye fits that bill perfectly.
If this bids true I fully expect Gilmour 100% to be brought in too. Alongside the workrate and physicality of Gueye and Onyana you could play Gilmour in a 3 with ease.
Matt Law who has great Chelsea/Lampard connections pretty much said the same thing yesterday about Gilmour