Leeds United slumped to a first defeat this afternoon.
Marcelo Bielsa's side slumped to a first defeat of the season this afternoon when Swansea City beat them 1-0 in a top-of-the-table Championship clash at Elland Road.
Leeds had more than enough chances to kill off the game long before Wayne Routledge's last-minute winner.
Costa, on a season-long loan from Wolverhampton Wanderers, was only given an 18-minute cameo and the Portuguese winger is still waiting on his full Championship debut under Bielsa.
In contrast, Harrison, who re-signed on loan from Manchester City this past summer, has started all six of the Whites' league games this season.
And Whelan has admitted that although the 22-year-old - who earns £51,000 per week [Spotrac] - has been solid, he wants the Wolves-owned star to be given a chance.
He told BBC Radio Leeds: "It's not easy for the manager to pick teams. Helder Costa I'd love to see start from the beginning. Maybe Harrison drops out for a bit, but he's done so well."
The West Yorkshire side visit Barnsley after the two-week international break on September 15.
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