New Arsenal left-back Kieran Tierney returned to Celtic over the weekend.
The Scotland international completed his £25m transfer to the Emirates Stadium on deadline day last week, but wasn't available for the Gunners' Premier League opener against Newcastle United.
This is because of injury and the 22-year-old isn't expected to feature for at least another month.
Instead, Nacho Monreal started at left-back as Arsenal kept a clean sheet at St James' Park and got their season off to a winning start thanks to Pierre-Emerick Aubameyang's
As the Gunners were away from home, there was no requirement for Tierney to make the trip to Tyneside and cheer on his new teammates.
Therefore, he took the opportunity to pay a visit to his ex-Hoops teammates and manager Neil Lennon.
"He was in yesterday. He popped in and everyone was delighted to see him," Lennon told reporters. "He got a nice farewell from the players and it was emotional for him.
"But the players will get on with it now and that's what you do, you roll on.
"He's going to be a big miss obviously but there's an opportunity there for someone else to take on the mantle now."
Despite being an Arsenal player for less than a week, Tierney has already made his mark by breaking a training record previously held by Aubameyang.
In a behind the scenes video released by Arsenal , the full-back is seen completing his medical, including doing the vertical jump and registered a height of 50cm in his first attempt and opted to challenge the Gabon striker.
And he passed it with flying colours.
He completed the challenge with just his second jump - registering a height of 55cm, beating his teammate by just 1cm.
The jump received a positive response from Gunners defender Rob Holding who was watching on.
