In a Group H match at Mestalla stadium filled with thrilling end-to-end action late on Wednesday, Chelsea seized the initiative over the first 15 minutes and pinned the hosts deep in their area of the field.
Valencia, however, managed to weather that early storm and then had a golden opportunity to score at the 19-minute mark, but despite being unmarked at the far post Maxi Gomez was somehow unable to get his foot on a cross from Rodrigo, reports Efe news.
Hands clutched heads in disbelief, although that blunder became easier to tolerate 20 minutes later when Carlos Soler received a pass from Rodrigo and volleyed it over the line off the hands of Chelsea goalkeeper Kepa Arrizabalaga.
The 1-0 lead sent the crowd into an intense euphoria, with the round-of-16 tantalizingly close at that juncture.
But the joy was very short-lived. Just two minutes later, the Premier League powerhouse capitalized on a failed clearance to strike at the other end, with Mateo Kovacic firing a low shot from just outside the area into the bottom corner of the goal.
Chelsea then took the lead for the first time just five minutes into the second half when a goal by American star Christian Pulisic was initially disallowed for offside but then permitted to stand after a VAR review.
Frustration for the LaLiga side then turned to exasperation when Rodrigo”s shot over an onrushing Kepa went just over the crossbar in the 57th minute and especially after Dani Parejo failed to convert a penalty chance in the 63rd minute.
But Valencia kept insisting and finally got a lucky bounce in the 82nd minute when an apparent attempted cross by Daniel Wass sailed too far and bounced off the far post and over the line.
The home side then had a chance to secure three points deep in second-half stoppage time, but Rodrigo was unable to convert a chance at the far post off a pass from left back Jose Luis Gaya.
Chelsea and Valencia are now tied atop Group H with eight points, while Ajax is in third with seven but could jump into first if they can hang on to a 2-0 lead and defeat Lille on Wednesday night.
The two teams qualifying for the round-of-16 out of that group will be decided in two weeks when Valencia take on Ajax in Amsterdam and Chelsea host Lille in London.
In other action on Wednesday night, Zenit Saint Petersburg notched a big 2-0 win over Lyon at Krestovsky Stadium.
Artem Dzyuba opened the scoring with a potent header off a corner kick at the 42-minute mark, while the hosts added an insurance goal the 82nd minute when a shot by Magomed Ozdoyev ricocheted off Lyon defender Marcelo and into the back of the net.
The result puts Zenit in second place in Group G with seven points; with one group-stage match remaining, the Russian-league squad is trying to beat out Bundesliga club Leipzig (nine points) and/or Ligue 1 side Lyon (seven points) for a knockout-stage berth.