Monday was a difficult day for tacticians in Valencia. A light breeze shifted 180 degrees over the course of the first two matches of the Louis Vuitton Cup Semi Finals. In fact, on the final run, the boats started under spinnaker and finished under genoa, tacking for the finishing line. Emirates Team New Zealand and Luna Rossa Challenge prevailed in the tricky conditions, drawing first blood in the "first to five" semifinals. Here's a wrap-up of both matches courtesy of ACM: Match 1Luna Rossa Challenge beat BMW ORACLE Racing by 2:19In the pre-start it looked as though Luna Rossa might be able to close BMW ORACLE Racing out above the Race Committee boat, but Chris Dickson and his afterguard had factored in some current sweeping across the start line. The American boat slotted in nicely next to the RC boat with Luna Rossa just to the left. After sailing locked together for many minutes, which seemed very sensible with the wildly shifting offshore breeze, the Italians and Americans broke away to opposite sides of the course. Luna Rossa tactician Torben Grael found the better breeze to the left and the Italians rounded 52 seconds ahead. Around the top mark, USA 98 picked up a beautiful puff of breeze and surged down the right-hand side of the course. The Italians meanwhile had already gybed off to the centre of the course and were wallowing by comparison. Dickson recouped a 400 meter deficit to put Luna Rossa helmsman James Spithill under pressure at the leeward gate, Dickson initiating an aggressive luffing match. Spithill did just enough to claim the left-hand gate mark while the Americans peeled away to the right, just 7 seconds back. Again both boats gambled with their respective sides of the course and again the Italians' faith in the left paid off as they leapt to another 400-metre lead. This time the Italians did a better job of shadowing the Americans down the final run, and even when the breeze shifted nearly 180-degrees just before the finish, Luna Rossa capitalised on the changeable conditions and stretched the winning margin to over two minutes at the finish. Match 2 Emirates Team New Zealand beat Desafio Español 2007 by 0:43If the Italians and Americans were playing their match fast and loose, Emirates Team New Zealand took no such chances. Dean Barker won the right-hand end of the start and it wasn't long before the Kiwis had established a small lead over Desafio Español 2007. After winning the lead from the right, Barker dragged the match to the left-hand layline and led Karol Jablonski to the first mark by 1:03. However, with the Kiwis sailing very defensively they yielded some of that lead to round the left-hand leeward mark by just 41 seconds. The Spanish brought the match even closer up the final windward leg, rounding 30 seconds behind at the final turning mark. As new breeze filled in across the course, and the teams were forced to douse spinnakers in favour of jibs for some close reaching to the finish, the Kiwis extended away to win by 43 seconds at the finish.For more Cup coverage, click here.