The right-back had already made a fine contribution to proceedings at Wembley Stadium before producing a moment of individual brilliance to rescue the tie.
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City’s lead, gained with a 12th minute Raheem Sterling strike against his former Club, had already been cancelled out late on through Joel Matip when Liverpool pressed for a winner deep into injury time.
Mo Salah – a threat throughout – thought he’d found one, looping a header over Claudio Bravo, which looked destined to bounce into the net.
Walker clawed City from the jaws of defeat however, somehow executing a perfectly-timed and incredibly effective overhead kick from the goalline to hook the ball away in the nick of time.
The clearance ensured the contest ran to penalties, which the holders would go on to triumph 5-4, with Bravo denying Georginio Wijnaldum from the spot.
Reflecting on his moment of magic, Walker remained humble but admitted he enjoyed it.
"I'm a defender,” he shrugged. “I stop goals.
“I'm glad I can help the team out this time. They help me out all the time by scoring goals so that one is for them.”
Walker also expressed his delight to have retained the trophy for the traditional season curtain-raiser.
“It's the first trophy you can win,” he continued. “For me growing up, the Community Shield was a big one.
“It starts off the season. We can start our momentum, and hopefully we can replicate what we did last season.”
With the Premier League’s Champions and runners-up locking horns at Wembley, Walker was also asked whether he expects Liverpool to prove City’s main title challengers once again.
“It's too early to say,” he admitted.
“There are a lot of good teams in this league but hopefully, we can be up there or thereabouts in all competitions."
Meanwhile, Kevin De Bruyne was pleased with City’s display and the workout it provided in a challenging but entertaining contest.
“It’s always going to be tough,” he conceded. “There are going to be moments in the game that we control and moments that they control, especially at this stage of the season.
“I think we defended well at times. We could have scored, they could have scored. It was a really open game.
“The good thing is that we always play the same system so we know what we have to do in the style we play.
“Some of the guys just came back two days ago and the rest of us have had a few weeks.
“I think the month of August is really important to get your fitness up, to get game time.
“For most of the guys, it was their first 90 minutes of the season so it was a really important game in that sense.”