The French star will turn 20 when Cupid fires his arrow and it was his sweet left foot shot which made sure of a second 2-0 win over Killie in succession.
Namouchi showed tremendous composure as he took a pass from man of the match Emerson to clinch the points 15 minutes from time.
But the only reason he appeared on the field was due to a knee injury suffered by Capucho in a challenge by Garry Hay which undoubtedly soured an otherwise decent night for the Light Blues.
It was not a vintage Rangers performance but there were a lot of pluses for McLeish – especially the comeback of Emerson – and the manager was simply hoping that Capucho’s setback was not serious.
Scotland supporters remember all too vividly how useful Frank de Boer can be in the air from set pieces as he headed in the fifth goal from a corner during the nightmarish six-goal Euro 2004 play-off hammering in Amsterdam three months ago.
Kilmarnock clearly didn’t learn the lesson as they allowed Holland’s captain to instigate the opening goal after 22 minutes.
Rangers won a free kick on the left side of Killie’s box after Michael Ball had been unceremoniously bundled to the floor by David Lilley. The severity of the challenge prompted Mike McCurry to issue a yellow card but there was worse to come for Killie.
Fernando Ricksen spotted the near post run of de Boer as he whipped the dead ball over and Frank glanced a header towards the back post. It was heading for the net but skipper Craig Moore made sure, forcing the ball over the line to claim his first goal of the season.
It was all Rangers deserved after a sprightly opening to the game with Emerson back in the side for the first time in over two months.
The Brazilian midfielder looked a little rusty, but his confidence on the ball was apparent as he tied to build moves from a central area.
Indeed he even tried his luck from distance in 13 minutes after some terrific work on the right side from Capucho but his shot from 22 yards was well stopped by Francois Dubordeaux at his left hand post.
Emerson also supplied a super pass to release Michael Ball, who had burst forward from the left back area to try a left foot shot in 30 minutes but it flew over the top.
A minute late Christian Nerlinger had an opportunity at the back post when the ever-improving Mo Ross delivered a great ball from the rignt but the German midfielder headed wide.
Then just before half-time Ross showed his quality again when he produced a good ball from the angle of the box, Michael Mols got his head to it, but Colin Nish got back to divert the ball wide for a corner.
Rangers looked sharp in the opening minutes of the second half too as Emerson played a terrific 40-yard ball down the right for Capucho to chase. The Portuguese star produced a decent cross but it was just too high for Mols.
Killie hardly had time to catch their breath when Nerlinger came marauding forward and evaded three challenges before lining up a left drive but Gordon Greer just did enough to force him to shoot wide.
Rangers continued to force the issue and enjoyed a 10 minutes spell when Killie could scarcely get out of their own half. Ross and Capucho both produced decent crosses into the box but there were no takers.
Then in 61 minutes only the alertness of Dubordeaux stopped Emerson from putting Rangers further ahead. Nerlinger’s corner broke to the the Brazilian who drove a low shot to the left corner but the Killie keeper was equal to it.
The frustrating aspect for Alex McLeish was that his side had not made the game secure by this stage and the tightness of the scoreline was all to apparent when Killie came desperately close to equalising in 63 minutes.
Frank de Boer conceded a corner on the right side and Rangers looked to have dealt with Garry Hay’s delivery but the ball broke back to the Killie full back.
Hay had only one thing on his mind as he hammered a left foot shot from the angle of the box and the ball smacked off the crossbar with Stefan Klos stranded.
It was a wake-up call for Rangers but there was more bad news for McLeish eight minutes later when Capucho, who had been having a highly productive night, was forced out of the game by Hay.
The Killie fullback was late with his challenge, catching Capucho on the right knee and the stretcher was called for.
Hay was shown the yellow card but it was hardly consolation for McLeish who watched another injury problem materialise.
Hamed Namouchi was sent on to replace the UEFA Cup winner and his introduction could hardly have been more timely.
Within three minutes the French-Tunisian scored the second goal that made victory sure and it was a quite excellent goal.
Emerson, relishing his return to the top team, created it with a slide rule pass into the teenager,
Namouchi then stepped inside to fool Hay and swept a low left foot shot into the right corner and the game was won.
RANGERS: 1-Klos; 21-Ross, 3-Moore, 5-F. de Boer, 18-Ball; 2-Ricksen, 4-Emersom, 8-Nerlinger; 20-Capucho (37-Namouchi 72), 10-Mols (9-Ostenstad 66), 14-R. de Boer.
Subs not used: 22-McGregor, 16-Vanoli, 32-Hutton.
KILMARNOCK: 28-Dubordeaux; 2-Lilley, 3-McLaughlin, 5-Greer, 24-Hay; 7-Fowler, 11-Skora, 29-Dodds (18-McDonald 84), 27-Invincible (19-Murray 67); 21-Nish (9-McSwegan 64), 12-Boyd.
Subs not used: 1-Meldrum, 6-Dindeluex.
Bookings: Lilley (21), Hay (70)
Ref: Mike McCurry.