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The former Lazio striker, who arrived from Lazio earlier this week, netted his first goal for the Hammers, as they scraped past their EFL Championship opponent at London Stadium.

West Ham saw QPR goalkeeper Joe Walsh keep out Max Kilman's close-range header and Richard Kone clear Jarrod Bowen's header off the line, before it broke the deadlock in first-half stoppage-time.

Ten additional minutes were played because of an injury to Konstantinos Mavropanos, who left the field on a stretcher, with Crysencio Summerville lashing home to ensure the hosts went into half-time with a lead.

The visitors responded in the 65th minute, with Kone outjumping Aaron Wan-Bissaka to nod home Karamoko Dembele's cross, and ultimately forced extra-time.

Eight minutes had elapsed when Summerville turned provider for the winning goal, as his inviting centre was met by Castellanos's fierce header to take the Hammers through.

Elsewhere, EFL League One Mansfield Town claimed the scalp of EFL Championship side Sheffield United, holding on for a 4-3 victory having led 4-1 at Bramall Lane.

There were no such problems for Norwich City, with Jovon Makama's hat-trick helping it to a 5-1 rout of Walsall, while West Bromwich Albion and Hull City advanced after penalty shootout victories over Swansea City and Blackburn Rovers, respectively.