The 26-year-old hadn't played a single Premier League fixture nine months ago, but 12 clean sheets and a Player of the Year award later, the Clarets goalkeeper is heading to the World Cup in Russian Federation.
Pope had his first minutes between the posts, and it was Welbeck, who replaced the Leicester striker in the second half, that closed the score with a header.
Japan's Hiroyuki Kimura heads to Elland Road.
England return to the Broad Acres for the first time since March, 2002 when they host Costa Rica at Elland Road tomorrow night in front of a sell-out crowd. We have only taken two (warm-up games) as we had some players in the FA Cup final and a couple in the Champions League final.More news: Fall Out Boy jams before Game 4 of Cup Final
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And things got even better for Rashford shortly afterwards, when he gave England the lead with a truly brilliant goal.
The victory ensured Gareth Southgate is unbeaten in 10 matches since he took charge in June a year ago.
The second half was a more subdued affair in terms of chances, the ten substitutions perhaps affecting the game's flow.
It was just reward for a fine first-half performance but England lost some of their rhythm after the break, as Southgate made a number of changes, including handing goalkeeper Nick Pope his first taste of worldwide football. Should Alexander-Arnold impress against Costa Rica, Kieran Trippier could lose his place.
Harry Kane, Raheem Sterling, Jordan Henderson, Jamie Vardy and Dele Alli were all involved in the session on Wednesday morning, as was Burnley goalkeeper Tom Heaton who is on the standby list for the World Cup squad.
Substitutes not used: 18 Patrick Pemberton, 23 Leonel Moreira, 2 Jonny Acosta, 6 Oscar Duarte, 9 Daniel Colindres, 10 Bryan Ruiz, 13 Rodney Wallace, 14 Randall Azofeifa, 24 David Ramirez.