Victor Moses's 61st-minute header looked to have capped a workmanlike, if not sparkling, performance but a Hernandez strike from the edge of the area foiled the visitors' bid to regain top spot.
Victory would have provided a welcome distraction while storm clouds from the Mark Clattenburg allegations still hover but Swansea, as awkward opponents here as they were against Manchester City last week, did not deserve another defeat.
It was a match that held promise for the purists and there was pep to both sides' early play, Oscar and Eden Hazard dangerous on the edge of the area and Swansea keen to counter down the right.
A third-minute break saw Hernandez send Angel Rangel through, albeit from an angle, but defensive caution kicked in and the pull-back to Michu meant the chance was wasted.
The visitors played keep-ball tidily but too often wove patterns too elaborate, Michu's first-time volley from a Hernandez chip over the top a rare act of decisiveness (13).
Chelsea's threat came chiefly from set-pieces but Leon Britton was on the line to stop Branislav Ivanovic sliding in at the back post and Fernando Torres saw a couple of headers land safely in Gerhard Tremmel's gloves.
Di Matteo might have been aggrieved to see Ashley Williams not punished for a clumsy tangle with Hazard soon before the break but the first half had been even, the killer pass elusive for both teams.
On came Ramires with licence to feed the forward line and he looked to have stirred some impetus when Moses followed up Hazard's low drive with a header that dropped narrowly over the bar.
But Michu provided a scare at the other end before the former Wigan man finally made the breakthrough with another header, only the deftest of touches needed to direct Gary Cahill's flick-on past Tremmel.
Michael Laudrup turned to Danny Graham and Nathan Dyer as the hail pummelled the turf, the latter's cross-cum-shot making Cech backtrack.
But the hosts finally profited when Itay Shechter teed up Swansea's record signing to drill low into the corner, the point lifting Laudrup's side towards the tantalising comfort of mid-table.
|Swansea City||Team Statistics||Chelsea|
|0||1st Half Goals||0|
|3||Shots on Target||5|
|4||Shots off Target||2|
|47.4||1st Half Poss.||52.6|
|58||2nd Half Poss.||42|