The war between Tyreek Hill and Crystal Espinal is still raging on ... TMZ Sports has obtained new court docs which show the Chiefs star is fighting with his ex to share custody of their son.
Crystal obtained sole legal custody of her and Hill's child back in February 2018 ... but Hill claims he's had a huge role in his 4-year-old son's life nonetheless.
In the docs -- filed last week -- Hill says even though Crystal was awarded custody in 2018 while she lived in Arizona ... he traveled at least 8 times to visit and develop a relationship with the child.
He claims when he asked Espinal for even more substantial time with his son ... she denied it unless she was allowed to move in with him in his Kansas home.
Hill says she ultimately ended up moving in with him in Kansas around September 2018 ... and he claims he's played a key parenting role with his son ever since.
But, in the court docs, he alleges that after his relationship with Espinal went sideways over child abuse allegations earlier this year -- he's only been allowed minimal time with his son.
The 25-year-old is now fighting like hell to change that ... asking a Kansas court to give him joint legal custody of the child.
In the docs, Hill says if the amount of time he spends with his son is left up to Espinal, it would be "devastating" to his relationship with the boy.
He also says under their current arrangement, his role as an active parent "is being disrupted at a critical point in the child's life."
As we previously reported ... Hill and Espinal are also in a legal battle over their other two children -- who were just born this year.
Espinal filed docs in July asking the court to give her sole custody of those kids ... and also demanded a paternity test to prove Hill is the father.
The two -- who are now broken up -- have had a rocky relationship dating back to Hill's time at Oklahoma State ... when the WR was convicted of domestic violence over a 2014 incident with Espinal.