The latter made an instant impact with a perfectly-timed run that was finished with a towering header in off the crossbar. The perfect start for Rangers and him on just his second league start.
However, a procession to a straightforward three points didn’t materialise as Livingston fought back and looked strong.
Yengi exposed Rangers’ centre-backs and ran clear, coolly finishing under Jack Butland to level. Shortly after, it was so nearly worse for the home side.
Yengi saw his close-range shot divert off Fernandez’s arm. It was on target, but a foul wasn’t given. The guidance from VAR HQ was that the defender’s arm was deemed to be in a natural position and the ball to be struck from close range.
Martindale and his team will likely disagree with that judgement. It was a crucial call that will likely be dissected, not least given referee Ross Hardie was not called over to the monitor to review.
As the game wore on, Livingston were comfortable for the large part.
Djeidi Gassama somehow missed on the counter before Yengi was superbly denied when clean in on Jack Butland.
In the dying seconds of injury time, substitute Robbie Muirhead fired just over as Diomande’s late, controversial, tap-in ultimately proved the difference.