Smith suffered the exact same injury four years ago when he dislocated his ankle and broke his leg against Liverpool in the FA Cup simply blocking a shot.
And the 29-year-old - now at Newcastle - rarely returns to Old Trafford but witnessed Valencia's horror at this week's Champions League clash first hand because a friend got him ticket.
Mirror images: Alan Smith (left) is carried off breathing oxygen in 2006 with Antonio Valencia following suit this week.
With Valencia expected to miss the rest of the season after his fracture and dislocation following a routine challenge from Kirk Broadfoot, Smith revealed being there brought that match at Anfield in 2006 flooding back to him.
'I can relate to what Antonio is going through. There's no getting away from the fact it is a hard road back from an injury like that but with determination, you can do it.
'I really felt for him and it brought back memories of my injury at Anfield.
'It's strange sometimes what causes serious injuries. Mine was caused by blocking a free-kick when there was no one near me.
.United players comfort Smith and Valencia.
'I just hope, like everyone in football, that Antonio can work his waythrough rehab and wish him all the best for a complete recovery.'
Smith was out for eight months but it took 18 months for him to fully recover.
However he knows that Manchester United is the best place to be when recovering from a serious injury and told The Sun: 'Valencia is in good hands. United's medical team are excellent and always keep your spirits up.
.and both suffered serious injuries from innocuous incidents, Smith blocking a shot from John Arne Riise and Valencia bumping into Kirk Broadfoot
'He will get so much support from the fans too. They were alwayssending me messages while I was out and I'm sure it will be the samefor Antonio.
'Being out like this means weeks of doing virtually nothing then long days with the specialists, the physios and in the gym building your ankle up before you can even think about kicking a ball again.
'But the thought of being able to get back on the field is what keeps you going, no matter how far away that day may seem.'
Ferdinand: I need five more games to reach my peak with Man UnitedMan United boss Ferguson makes 9am dash to Valencia's hospital bedsideRound-up: Mourinho passes Real test. but fans jeer superstar Ronaldo Thank Roo! Rangers star Kirk Broadfoot grateful for Wayne Rooney's words after Antonio Valencia horror injuryValencia will recover from horrific ankle injury, insist Manchester UnitedManchester United 0 Rangers 0: Ferguson's flops hit the wallMANCHESTER UNITED FC