Shackleton impressed at right back as Marcelo Bielsa's Whites finally bagged their first win of the new Premier League season through a 1-0 victory against the Hornets.
Diego Llorente's instinctive finish from an 18th-minute Raphinha corner proved the only goal of the game as part of a contest that Leeds dominated, mustering 20 shots on goal.
But Llorente's strike proved enough to seal all three points which took Leeds out of the drop zone and up to 16th after seven games played, three points clear of the bottom three.
Asked if the first win of the season came as a relief on LUTV, Shackleton admitted: "I think so.
"It took us a few games to get that first win but we have got it and it's something to go and build on now.
"We controlled large parts of the game and when you are on top you want to build up a bit of a lead.
"But at the end of the day that one goal was enough and we came away with three points which is the most important thing at the end of the day."
We’ve gathered the best of today’s Premier League chatter below...
1. Liverpool eyeing Bissouma
Liverpool have been tracking Yves Bissouma for some time ahead of a potential move and the Brighton midfielder is “preparing” for a big-money switch by showing more discipline away from the football pitch. (Transfer Window Podcast) (Photo by GLYN KIRK/AFP via Getty Images)
Photo: GLYN KIRK
2. Ashley won't sack Bruce
Newcastle United owner Mike Ashley won't sack manager Steve Bruce as his priority remains to find a buyer for the club. Ashley would have to hand Bruce and his backroom staff a pay-off to terminate their contracts early and therefore the Newcastle owner has backed him to turn things around. (The Sun) (Photo by Catherine Ivill/Getty Images)
Photo: Catherine Ivill
3. Tielemans targeted by Real
Real Madrid are keen on a potential transfer swoop for Leicester City midfielder Youri Tielemans. (El Nacional) (Photo by Justin Setterfield/Getty Images)
Photo: Justin Setterfield
4. Everton eye bargain Villar deal
Everton have been told they will need to pay £3.4m if they wish to sign Gonzalo Villar from Roma in January. (Fichajes) (Photo by JURE MAKOVEC/AFP via Getty Images)
Photo: JURE MAKOVEC