Manchester, May 4 -- Manchester United secured Champions League football next season as Kobbie Mainoo's strike earned a thrilling 3-2 victory over old rivals Liverpool on Sunday. United were 2-0 up inside 15 minutes through Matheus Cunha and Benjamin Sesko, but imploded after the break to allow Arne Slot's men to level with goals from Dominik Szoboszlai and Cody Gakpo before Mainoo secured the win. A return to Europe's elite competition after a two-year absence and another big game win furthers Michael Carrick's case to continue as United boss next season. Third-placed United open up a six-point lead over Liverpool and are guaranteed to finish in the top five....