Both sides have a player sent off as Cardiff edge to victory over the Dragons
There was little between the teams but Dragons will rue a host of missed opportunities when their opponents were down to 13 men for a 10 minute period in the second half.
Lawrence scored Dragons’ only try with Sam Davies kicking three penalties and a conversion.
It took Adams only 11 minutes to celebrate his Lions call-up by scoring the opening try of the game. Blues built up a sustained period of pressure with strong bursts from Jason Harries and Rhys Carre before a well-judged pass from Thomas sent Adams over.
Dragons then suffered two further blows. First Matthew Screech, a Cardiff player next season, departed with an injury before Davies was off target with a straightforward penalty attempt.
Thomas extended Blues’ lead with a simple penalty to give his side a 10-0 advantage at the end of the first quarter.
Thomas blotted his copybook by over-kicking a penalty into the dead ball area so Blues lost 45 metres and their opponents were able to enjoy a period of territorial domination.
The Gwent side threatened the try-line but lacked the accuracy to capitalise and the only score of the second quarter was a Davies penalty from the last kick of the half.
Five minutes after the restart Cardiff centre Lane was red-carded for a high challenge on Dragons scrum-half Gonzalo Bertranou and the visitors immediately capitalised.
From a lineout 10 metres out, Dragons went through the phases before Lawrence forced his way over with a conversion from Davies bringing the scores level.
Dragons should then have taken the lead but they chose not to take three points from a kickable penalty in favour of a more attacking option but it proved the wrong call as they blew their opportunity.
They learnt their lesson as Davies kicked the next penalty as Blues introduced international backs, Evans and Willis Halaholo, in an attempt to reverse their fortunes.
It did not pay immediate dividends as Cardiff were reduced to 13 when Harries was yellow-carded for a deliberate knock-on.
Davies kicked his third penalty before Harris returned in time to see his side regain the lead when their replacement Williams crashed over and Evans succeeded with the crucial conversion.
Dragons replacement hooker Lawrence was then sent off for a high challenge before Davies was wide with a penalty attempt from inside his own half.
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