Dan Robson is a bit part player for England but he is indispensable to Wasps, whose losing streak may have been extended to three matches without him. It was the scrum-half who provided the rare moments of inspiration for Wasps in a grinding contest that nearly fell victim to Covid-19. The Dragons were forced to make six changes to their 23 after two of their contingent tested positive on Friday. The organisers were told that night but informed Wasps less than four hours before the kick-off, after deciding the game could go ahead while the six players isolated. “I found it strange we were informed about this as late as 2pm,” said Wasps’ head coach, Lee Blackett. “We discussed it with our medical staff and then spoke to the players. We gave them the option of withdrawing, but they were happy to play.” Despite the late reshuffle, the Dragons frustrated last season’s beaten Premiership finalists, although they did not offer enough in attack to swing a hard-fought contest their way and were ultimately undone upfront. Wasps looked to play at a high tempo, yet they struggled to create space in what became a kicking contest. But there was Robson, ever alert to opportunity, and it was his defence-splitting flat pass that created the game’s opening try for Tom Cruse. The manoeuvre caught the Dragons’ scrum-half, Rhodri Williams, in two minds, and he was similarly bewildered on the half-hour when Lima Sopoaga feigned to return a kick in his own half but ran instead, and then linked up with Josh Bassett. The wing fooled Williams with a dummy and ran to the 22 before passing inside to Robson. That put Wasps 12-3 ahead with Sam Davies kicking one penalty and missing another in between the two tries. The Dragons were comfortable with Wasps taking the game to them through the hard-running Jack Willis and Alfie Barbeary, but far less so on the few occasions the game became unstructured. Wasps had scored their first try as the Dragons wing Jared Rosser was trudging to the sin-bin after a no-arms tackle denied Zach Kibirige a try. Wasps lost Sopoaga to the sin-bin three minutes into the second period for another shoulder challenge, on the onrushing Josh Lewis. The Dragons exploited the advantage as passing that had been laboured all evening became crisp as Nick Tompkins, Lewis and Jonah Holmes moved the ball to Jamie Roberts on the left, where he perfectly timed his inside return to Holmes for a try. Davies missed a 40-metre penalty that would have reduced Wasps’ lead to a point, and the Dragons’ Covid changes cost them when Aaron Jarvis, who had been penalised twice in the first half for hinging, was sent to the sin-bin after 55 minutes. Normally Jarvis is replaced around that time, and no doubt would have been had the Wales international Leon Brown been on the bench. Two lineouts later, Willis sealed a victory that was decorated with a bonus point seven minutes from time by Thomas Young, after another telling Robson pass. But Wasps are still striving for the fluency that took them to the Premiership final.