Tim Weah marked the start of his loan spell at Celtic with a goal against Airdrieonians in the fourth round of the Scottish Cup. United States international Timothy Weah scored on his debut for Celtic as the Scottish champions beat Airdrieonians 3-0 to progress to the round of 16 of the Scottish Cup. "It's really a dream come true,'' Weah told the BBC. Weah, 18, is on loan from PSG and, 14 minutes after coming off the bench, ran onto a Dedryck Boyata through ball to put the finishing touches to the game with the final goal in the 83rd minute. Transfers How a transfer works With help from former Tottenham and Liverpool director of football Damien Comolli, we show you a step-by-step guide to a transfer. What's a medical like? Can a 44-year-old man cut it in the Premier League?